Plus, right now you're doing web and android dev, but maybe you'll take a class that will open your eyes to other areas. Maybe you'll find out you love compilers or computer vision or parallel computation.
There are a lot of people on HN who love to be contrarian or want to beat the system by proving they could accomplish X without a formal education which they believe is more about credentials than actual education. But the truth is, not having the degree is just going to make your life a lot harder, plus you might miss out on learning things you wouldn't self-study.