<insert garage success theory - starting with only coffee and a computer>
I understand it's not just coffee and a computer. You have to take into account the time that you give up from a 9-to-5 that you would make money from, but all things being equal, compared to lawyers, doctors, 'management suits' type of people, you are not directly dependent on others to start out.
Build a useful product, and they will come.
I think that the 2010s will be dominated by self-started firms that evolve from consulting into product spaces, but most of that activity will not be in the startup hubs (e.g. Silicon Valley, New York, Boston) because the burn rates are too high. The geography of that growth spell will be very different from what we're used to.
I think the way out is to become an "X Who Programs". You become something else-- financial quant, startup founder, game designer-- who also happens to be a programmer. The reason this is so powerful is that no one (except a top programmer) can evaluate programmers, which creates nasty politics as people jockey for visibility, so you establish yourself in your more-visible X but use programming as a secret weapon. It keeps you from being treated like a commodity programmer and also gives you an edge on the best projects.
XWP is what the data science phenomenon, in truth, is. There, the X is statistical knowledge.