It also requires a degree of knowing your worth, asking more than your worth, doing insane amounts of work and being very good at pricing and marketing yourself.

I personally don't care that much about money, so I tend to work for a year or two and then take a year off:

http://khanism.org/perspective/minimalism/

Unlike a lot of other careers, this isn't as difficult to do in software, and you end up working for better companies who care less about having a warm body that will stay there forever over having someone who can think creatively.