For me it was too exhausting to constantly come up with new and original content. I was planning on doing only internet based work at some point but I realized that although it's safer, it was even more exhausting for me. I felt like I would have to do more and more extreme things and felt a pressure to be hypersexual.
This !
I mean unless someone is extremely popular and for some reason guys still pay to see the same boobs in videos they seen a hundred times (Alinity comes to mind), eventually peoples want more. And yes if someone is very creative, they can "get away" with doing nude only or even no nudity (but lingerie for instance) but thats a LOT of work. You can't just take selfies or yourself in your bedroom. We talking pro-shoots, costumes, venues. All this cost money.
But usually everybody that do become "big" on OF are because they have other things goin on. I mentioned Alinity, she was a streamer before doing OF and gain a following there. Someone like Paige Van Zant was a fighter and has massive following because she was a hottie long before OF.
Lets say you start from scrratch, you are average Jane (but you very pretty) but have "only" 5 to 10k followers, you don't stream video games or other content, like you just switch from escort to OF, its gonna take time to built enough to make a good pay and in the end, you may feel exhausted of all the work you have to spend replying messages and actually shooting the content.