ML inference should cost a lot more to run than typical SaaS too... that said, I'd pay more than $20/mo for access to GPT4 or Claude 3. It is worth at least $75/mo to me. I pay for both right now just in case one is better than the other for a certain task (though I might drop GPT soon).

Because I'm willing to pay for it?

It is already norm in too many places to get that maximum revenue…