Don't think it's solely about the money. Reputation, history, everything else is in the mix. Of course Twitter would have an excellent argument that porn is only a tiny subset of its content and it has much larger, legitimate uses.

As a founder, you don't have that reputation and track record to point to, so you'll need to be more careful, especially in the early days.

But I doubt it's about the pure dollars and cents. There's plenty of money in porn, even now. It's about having a plausible story to tell the card companies and PR. Twitter and Reddit are safe, and it's about that story, not steak dinners.