Most enterprise GPUs are scrap after 5 years because they're so inefficient compared to newer models. It's entirely possible to make them last longer by undervolting them, people just don't because it doesn't make sense.

Bitcoin OTOH has used the same PoW algorithm for a decade. Barring some really exciting discoveries about the nature of computation, new ASICs are not that much more efficient than old ones.

BTC mining is also not exactly competitive anymore; the nature of the PoW algorithm means that it's dominated by a few large players who've set up shop next to a dam and who pay very little for electricity.

New entrants are highly discouraged because the mining rewards are constantly halving, it's hard to find cheap power, and the price of BTC is now so volatile that a yearslong investment is very likely to lose money.