I think it's important we remind ourselves of how credit cards work.
It's the credit card company's money, not the surfer or ours.
The lender purchases that membership. And the surfer pays back the lender at a later date for that purchase.
So, really, I have trouble faulting the credit card networks for working to protect their own money. Because it is their money.
And, really, when credit cards are involved in the process we as online merchants never actually get money from the surfer themselves. We get it from the lender.
So I simply can't find fault in Visa demanding that fee. It's their money! It's entirely up to them who they want to give it to and who they don't want to. And there were enough bad apples in the barrel to leave the rest of us stuck with this $750 fee. And we just gotta live with it.

It's now a basic business expense. We know full well we engage in a high-risk industry where there are complications and issues unique to it and unlike any others faced by those in different industries.

Our bandwidth usage is high because of all the video we stream and make available.
Our competition is fierce because there are so many other adult sites like ours out there.
Access to our websites need be controlled because of the kinds of content that rests on them.
Legal issues concerning our content and sites are different than those faced by others.
We see lots of naked people.
Those are just some of the inevitable and everpresent, definitive aspects of this industry. And a $750 Visa fee is now one of them.

There is no entitlement here to credit card processing. We don't have a right to it. It's the lender's money and when one of those lender's with a 60% market share throws a new rule on the book, we gotta accept it.

Of course, their are always other options. Not processing that particular card. Not doing business in this country. Not accepting credit cards at all. Arranging for some other type of payment set up that doesn't involve Visa. But then that is a business decision just like moving hosts or upgrading to a new server or buying advertising or redesigning your site. Just one of the many decisions that has to be made by a business. Weigh the pros and the cons and if it makes financial sense then go with it. Business.

Just business.