Bitcoin halving and network security: will miners keep it safe in 20, 50, 100 years?

ok so everyone here loves to panic about quantum computers that probably won't exist for another century, but nobody talks about the actual threat sitting right in front of us? Miners secure the network. We all know that. But their BTC reward gets cut in half every four years. So unless the price roughly doubles each cycle, mining becomes less and less profitable and eventually people just... stop. Right? Look at the 200 SMA, it was around $50k a couple years ago, now it's around $100k. So yeah, it's holding up for now. But the rate of price growth is clearly slowing down. At some point this math stops working. Why is nobody taking this seriously?

If people in 2050 still find bitcoin useful, they'll use it to actually transact with it. And if they transact, there will be fee revenue. Right now avg block fees are tiny, like 0.015 BTC per block over recent history. At today's prices that's peanuts. But if BTC hits $10M? That same 0.015 BTC becomes $150k per block. That's very much worth mining for. The real question nobody's asking is: will average block fee revenue still be around 0.015 BTC in 2050+? To get any kind of answer you have to look at what happened historically when BTC was worth way less than now and see how the fee market evolved...

fees already carry more weight than people give them credit for. bitcoin currently generates more in fees alone than several competing chains produce from fees AND inflation combined. so a bitcoin without a block subsidy isn't some crazy uncharted territory, it's already more viable than a lot of live networks operating right now. where it gets tricky though: inflation gives miners a constant reason to keep building on the longest chain. fees replicate that incentive only partially, through anti-fee-sniping mechanics. so in the future you might just need more confirmations before treating a tx as final. not the end of the world imo.

nobody said the price HAS to double. that's not a rule. Miners enter or leave the industry based on profitability. Fewer miners = lower difficulty = lower cost to mine. The network adjusts. Satoshi built two income streams into this thing: the block subsidy (which halves every 210,000 blocks) and transaction fees. The system isn't as fragile as you're making it sound.

the security budget has to scale with what's being protected, that's just basic logic. think about bike locks. you wouldn't spend $5 to lock up a $5,000 bike. you'd spend proportionally. same idea here. the cost to attack the network needs to stay painful relative to what an attacker could actually gain. comparing bitcoin's security to other blockchains doesn't really land imo, because those chains' total daily tx value is a fraction of bitcoin's. the comparison flatters the alternatives more than it should.

from discussions I've seen here before, people basically fall into two camps: hope the price keeps rising to offset smaller subsidies, or hope on-chain volume explodes so fee revenue fills the gap. problem with the second option is it implies bigger blocks, and that gets almost zero traction in this community. also worth noting some mining pools already refuse txs below 1 sat/vB, which is a whole other angle on this. and comparing this to other coins is genuinely hard because some of them pay block creators a percentage of staked holdings, completely different model.

if we're working from current avg tx numbers staying roughly static, you'd need bitcoin somewhere in the $800k to $1M range for fees alone to make mining sustainable. sounds wild but based on historical price trajectory it's not actually impossible before the last coin is mined. as for block space, yeah it's limited and nobody wants a fork to increase it, so that kinda naturally pushes users toward L2 like Lightning anyway. maybe that's the intended path.

here's the thing though, when BTC hits $1M the fee market won't look anything like it does today. ten years ago people were happily paying 100 sat/vB. now that's basically unheard of. why? because the fiat value of those sats got much bigger. people just won't pay $10+ for a median tx if they can avoid it. bitcoin tx fees are actually deflationary in sat terms over time. you can see it clearly in the data. so "more price" doesn't automatically mean "more miner revenue from fees" in the way people assume.

appreciate the stats shared earlier in the thread, genuinely useful stuff. one thing I keep thinking about: bitcoin wasn't originally pitched as digital gold, it was meant to be a payment system. somewhere along the way the narrative flipped. and honestly I get why, gold is clunky, it doesn't fit the modern world, and mining it causes serious environmental damage. bitcoin fills that store-of-value need digitally. but if it's mostly a settlement layer now rather than a payment rail, does that change how we think about fee sustainability?

yeah exactly, 100 sat/vB back then was worth basically the same in dollars as 1-5 sat/vB today. so the sats-per-byte number dropping hard doesn't mean miners are actually earning less in real terms, the data shows avg block revenue has stayed in a rough range over time when priced in fiat. that's actually the basis for my optimism here. sat/vB will keep falling but if price keeps rising it nets out. and yeah, block size pressure naturally funnels demand to second layers which ironically might make the base layer fee market healthier not worse.

the deeper problem imo is the supply algorithm itself. gold works as both money and store of value partly because annual production is roughly in line with demand growth, like 1.5% or so per year. there are short-term swings but it mean-reverts over long periods. bitcoin has no such feedback loop. the halving happens on a fixed schedule regardless of price, regardless of demand, regardless of anything. for bitcoin to function as actual money long-term it probably needs some metric tied to real economic conditions rather than a countdown timer. that's a hard problem and nobody really wants to touch it.

this has been bugging me too actually. why did anyone think it was a good idea to lower the minimum relay fee significantly? I haven't brought this up before but it strikes me as backwards thinking, especially when fiat-denominated fees have been dirt cheap for ages. personally I won't send anything below 1 sat/vB while fees are this low. yeah you save a few cents in the short term. but if this kind of thing quietly erodes miner revenue over time, we're trading a minor convenience now for a real security problem later. doesn't seem worth it.

ngl this whole thread is dancing around the real issue. the system as designed kind of eats itself eventually. Scrypt with merged mining (doge+ltc) is built differently, the inflation rate there tapers gradually rather than getting chopped in half arbitrarily. if crypto as a whole survives the next few decades I genuinely think scrypt outlasts sha-256 in the long run. I'm 69, so I probably won't be around to see how this plays out past 2056. but the math on the upcoming halvings is stark: each one basically doubles the minimum price needed to keep the same hashrate. that's not sustainable forever.

I don't actually see the supply schedule as the problem people make it out to be tbh. the coins weren't premined and handed to insiders, the distribution was open from day one. and think about what the alternative looks like: a smoothly declining subsidy (50 BTC, then 49.99999997, then 49.9999994...) would avoid the abruptness of halvings but would take an extremely long time to get the inflation rate anywhere near gold's. if Satoshi had gone that route we'd probably be sitting at around 18.75M BTC in circulation right now with meaningfully higher annual inflation. the halving model got us to a scarce asset faster. whether that was the right tradeoff is a fair debate but it wasn't random or careless.

there are a lot of scenarios here and all we can do is model assumptions. security is relative. if miners drop off, difficulty adjusts down and the remaining miners stay profitable. yes, total hashrate falls and yes that's a security reduction, but security isn't just raw hash, it's the cost to attack. bitcoin doesn't really do halfway, either it carves out a permanent place in the global financial system or it doesn't. if it's still running fine in 2050 that alone tells you it survived the hard part. the older the network gets the less likely a collapse becomes imo.

props for thinking about this, most non-technical people don't bother. the concern is real and not crazy. but here's the honest answer: nobody actually knows if fee revenue will be sufficient security once the subsidy hits zero. research is growing but predicting 50+ years out is just... hard. anyone claiming certainty either way is selling something. what matters first is being specific about which attack scenario you're worried about. without that the whole conversation stays fuzzy. a 51% attack by a state actor looks completely different from a miner cartel problem or a fee-sniping spiral. different threats, different mitigations.

here's how I think about the floor for "enough" security: as long as no attacker can get their hands on close to half the network's hashrate infrastructure, the level of security is sufficient regardless of the dollar amount being spent on it. 51% attacks in the wild have basically always relied on renting hashrate or hijacking machines with malware to grab GPU/CPU power. there's never been a documented case where an attacker actually owned the physical mining infrastructure and pulled it off that way. so the real risk question isn't "is the subsidy big enough" but "can someone ever realistically accumulate that much owned hashrate without the market noticing." that's a much harder thing to do than the doom scenarios suggest.