I'll bite: because after all is said and done, I believe we're more likely to have something of value left over from the AI craze than from the blockchain craze. The energy that goes into training a model gives you something that you can use afterwards; The energy consumption of Bitcoin is continuous (while still producing nothing of real use to anyone). Also, we can optimize the power used by machine learning, whereas optimizations in Bitcoin mining just mean everyone adopts it and the power goes back up (the nature of proof of work). So Bitcoin is hopeless, but to me the jury is still out on AI.

There's a separate question of whether the things we develop with 2020s-era "AI" will be good for us or worth all of the resources we put into it, but there are actual, valuable uses of things like image recognition and translation.