The difference is that, by design, the best (cheapest!) Bitcoin you can buy is the Bitcoin you buy today. It only gets more expensive as more people use it and the supply of new Bitcoin decreases.
By contrast, the ai we have today is the worst ai it will ever be. Quality will go up with time, and price will go down, as incentives drive the development of better, cheaper models.
Look at how neural voice synthesis has evolved over the last five years. It's gone from science fiction to extremely expensive to 'can run in real time on a phone' thanks to a combination of hardware and algorithmic improvements... But mostly algorithmic improvements.
Algorithmic improvements are coming quickly in generative ml. We're still in very early days.
By contrast, the ai we have today is the worst ai it will ever be. Quality will go up with time, and price will go down, as incentives drive the development of better, cheaper models.