Paid content like Onlyfans, Fansly etc is becoming more and more popular and viable because, believe it or not, people (mostly man) become more and more lonely. Covid didnt help with this either. So instead of going out, going through all the struggles of getting a one night stand from the club or actually getting a girlfriend that eventually cheats on you because she finds a slightly upgrade in another man they just pay 15$ and get the specific content that they want.
You want some 18 yo to send you feet pics? Feetfinder got you covered
You want NSFW ASMR? All these girls like maimy, puffin, claudy, bella etc got you covered
You want mommy content? Some mommys on OF got you covered
You want some femdom content? Internet got you covered.
You just gotta be ready to pay for it.
This obviously doesnt count for every guy that buys porn, be it normal porn or OF porn or w/e porn but its a big reason as to why this whole OF thing works.
Its not as bland and fake as normal porn, its way more personal and you have a waaaay bigger selection of shit. Also custom content.