Danni Ashe started in pre-web days. Back then I was surprised there was any money in it. Already usenet had more content than anyone could possibly stitch together and uudecode. The old BBSes had tons it and it was being posted to usenet every minute.
The early web was far easier to code and far less demanding to maintain. Anyone with a bit of intelligence could learn it quickly and do it themselves. What people demand today as far as an interface, java code, etc and so on would have a much steeper learning curve. I haven't coded websites in ages but unless there are special tools to do it all for people a DIY website that is good enough for commercial use these days wouldn't be nearly as easy. What that means is hiring people, so more cost.
Also another thing Danni Ashe did was hire others to model for the site. This constant newness had to have helped considerably. The single woman site logically would need to be finding new customers at a much higher rate. After a while there probably isn't much to see that hasn't already been seen. People move on. Honestly I am surprised any of them make enough money to eat these days (without having a regular job somewhere). The amount of competition, the lack of disposable income among regular people, etc has to make getting enough subscribers difficult.
She'll have to decide whether the site is worth the income it generates vs the work and how the numbers are looking with regards to subscriber retention and new subscribers. She's not going to go down the road of exposing more and more of herself to keep it going, so it's really a question seeing where the peak is and knowing when to turn it off. As one woman show, that is with limited newness, it's going follow some sort of predictable curve from the data she should have, provided there isn't some sort of mainstream TV exposure or some such that changes the trend.
Oh take a look at the January 31, 2014 at 10:02 am post by her. I won't quote it, just read it on the 30 link.