As for visits, you have to consider demographic splits. 50% of people are female who's viewing is going to be relatively minuscule, another x% are too young to be interested, another y% are going to be too old to be regularly interested, and so on. You get a surprisingly small slice of society. And now factor in the fact that there are about 8 zillion other sites. There's also the issue that when any country decides to ban porn, Pornhub almost always going to be target #1. For instance it's banned in India and China, so you're losing potentially billions of people from stuff like that.