Being able to point to a real product being used by real people who had paid me real dollars for it has made a significant difference for me in job interviews in the past, especially for my first real job out of college at Microsoft.
Today, I'm a startup co-founder. If I'm looking to hire a developer, and I see that a candidate knows how to not only create software, but also market it and sell it, AND that they recognize the value in those other two steps, I'm significantly more likely to call them in for an in-person interview.
And besides, with any luck you'll generate enough money off your own software that you can tell all those companies you're looking to for a job to piss off ;)