Fanfiction.Net is an odd case, because it started out like any other fan-run archive, and slowly evolved into a revenue generator over time. Everyone understood that initially the monetization was just to keep the whole massive operation going. There was plenty of forewarning, and like you said, nobody ever mentioned making a profit. Considering what those maintainers were dealing with back then, I think all that was on anyone's mind was the site's survival.

Opportunists are inevitable whenever there's the possibility of profit. Mander's not going to be the last of them. But after a few more of these operations crash and burn, I hope they may start to get the hint.