They literally charge a LOT for their services

$20 ARPU averages out to about $1 in profit in typical SaaS. Gotta generate more than that to make investors whole, unfortunately

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).

I'd prefer to pay for no-ad version.

You will instead need to pay and see ads at the same time!

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

Like with cable or how streaming services are headed?

Why would you be offered this option?

Because I'm willing to pay for it?

You may not be offered a choice because you will be paying even with advertising content present.

In case it's not clear - I'm willing to pay extra for this.

Ok, in this case the businesses will need to consider how many users are like you and how much tweaking they will be required to strip out the promotional material.

Then they will decide if to offer this functionality and at what price.