So, I think what you’re asking is how photographers make money out of this…? I’m not a photographer, and asking one might be a better thing to do since they will have insight that I do not yet have, but I will do my best. :)
Yes, there is income made from Zivity. As far as there being a “huge market”, there are many people that do well on Zivity. I know that they announced their highest paid photographer made $2k+ in just the 2nd quarter. So there is the opportunity to do well on there. I don’t know about selling to collectors, but I know that print sales can do well also. Many photographers do solo or joint exhibitions of their work and sell prints of what’s on display. They also can take part in larger shows such as the Seattle Erotic Arts Festival or Nude Nite Orlando/St. Pete. I know that prints of me have sold at shows like that for around $500 each. People also sell prints through online stores (I have one where prints are available). So you can also make a fair amount of money selling prints.
As far as who’s buying it, I can only guess. I know that many people subscribing to Zivity and purchasing votes are people serving in the armed forces and are overseas or just have a lot of disposable income. Some people are just fans and spend money on what they enjoy. Some people go to the art shows and see an image they love and buy it. I personally know a lot of photographers that like to collect work from other photographers they admire. All kinds of people spend money on the images; I don’t think it’s one type of person.
It is a side project or job for most photographers that I know and have worked with. While some models and photographers are fortunate to have been able to have figured out a way to fully support themselves while doing it, most have not and do it as a side hobby. Some have the intention of having it become a full-time gig, but many are content doing it on the weekends and days off. I wouldn’t say that it’s because they’re bored with their jobs at all. People are multi-faceted and art is often one of those facets. :)