AI/ML barrier to entry is far simpler and vastly user friendly compared to crypto. Instant value return or gratification from ML products (GTPs and rest) is far more mainstream friendly.
Another view is the "loss" factor. Nobody, thus far, has has had their funds stolen or lost using ML products. I understand content creators and those who, unwillingly, contributed knowledge to learning systems did get circumvented but i'm talking about users/customers. Compare that to the negative stigma of crypto frauds and stereotypical association to illegal transactions.
Apples vs. rotten oranges in my opinion!
A chatGPT user could just be someone who popped onto the website and submitted the chat form.
Meanwhile millions of people pay for tools that are now integrating AI to enhance their value add.
Free ChatGPT is just a loss leader for API and paid acct and a way to better train the model.
Most people who own crypto exchanged dollars for it.