I do my regular job but still spending 4-8 hours per day on my plugins. During vacation it goes up to like 18h a day. It's been like that for the last 2 years or something. But I never thought of "making a living" out of it.
That being said, you actually can do VaM without having to rely on income generated from it. Just do VaM in your free time instead of watching movies or something.
I don't want to sound cocky, but creating scenes or poses isn't exactly "hard work" compared to the issues I'm dealing with at times. So I cannot understand why people are charging money for it, considering this is a funny and arousing task to do (if not, you're doing something wrong).