Why has mining hardware changed so much?

I know this might seem obvious to some, but I'm really trying to wrap my head around why bitcoin mining moved from CPUs to GPUs and now to ASIC miners. I get that there are limits on block size, around 1 megabyte per block on average. But if that size hasn’t changed, what’s pushing the need for more advanced hardware? So, what’s really driving this shift?

The sheer number of miners and their ever increasing speed driving up difficulty. That in turn means you need more and faster miners to be able to find blocks on the industrial scale. Only ASIC-based miners have anywhere near the speed needed. Even a S3 from 2014 pushing just a few hundred GH/s is faster than the best GPU's available today.

With the help of CPU on GPU you can mine any coins, but ASIC on a certain algorithm can work like thousands of CPUs and GPUs, because this ASIC is designed for a specific algorithm. If you like this analogy, then in the past many people worked in the fields, but when the tractor was invented, the use of human labor became unprofitable.

There's no correlation between maximum block size and what kind of device used by miner to perform mining. Short version, actual mining operation is SHA-256D hashing on 80 bytes block header. The actual reason miner keep switching their mining device is to remain mine Bitcoin profitably.

competition and worldwide hashrate went up up up. back in 2012 I had 22gh in gpus. they mined about 1/1000 of the entire worlds network and burned 11kwatts. now due to competition the network is 1000 eh so 1/1000 is 1eh if you use the gpus I had 1000 gpus would do 1th 1,000,000 gpus would do 1 ph and 1 billion gpus would do 1eh. and burn 500,000 kwatts so no way I will be able to burn 500,000 kwatts which equals 500 megawatts in my garage. so asics do more work for less power. 4 s21xp do about 1 ph 4,000 s21xp do about 1eh this would have the same share of the network I had in parts of 2012 4,000 xps burn 14,000 kwatts my garage is not burning 14,000 kwatts or 14 megawatts to get 1/1000 of the network. so basically asics are here now because people fight for coins and they do it better. but people feed big money and way more power and gear is used.

The major reason behind what force the shift of the Bitcoin mining rig from CPU-GPU-ASIC is the level of mining competition, and for miners to mine profitably, they need to use a mining rig with good computing power. It's just like you working as a freelancer and you're using a 2G internet when other freelancers are using 5 G. You won't deliver your service to clients on time, and you'll lose clients while others with strong internet deliver their service early and gain more clients.

Mining difficulty keeps increasing and to stay profitable you need to increase the capability of your miner, that's where Asic miners comes in, they are more powerful and faster. Bitcoin mining turned into a competition in those days since 2016, hash rate starts climbing up as Bitcoin mining becomes more popular, it's no ones fault. Proof of work coins that laggs behind are less demanding in the public, can't be compare with Bitcoin, it will take thousands of graphic cards today to do the work of an old Asic miner that's no more profitable to mine Bitcoin today. I wish it's the other way around too OP, but it's just too late right now to easily mine Bitcoin, the demand is too damn high.

Hashrate Sinks to 8-Month Low—Golden Entry    Bitcoin’s hashrate has dropped to 684.48 EH/s—its lowest since October 2024—due to rising mining costs and energy-saving measures. A 9.5% mining difficulty drop on June 29 could boost miner profitability and help restore network strength and participation. Despite the hashrate dip, Bitcoin holds at $106,000, supported by ETF growth and resilience against stock market volatility. https://beincrypto.com/bitcoin-hashrate-sinks-8-month-low/