Some things to consider - there is a certain glamour to the startup life, and certainly you can make it big. Statistically however, you will lose money - so if you are chasing gold, chances are it's a pipe dream. Certainly there's a chance, but you are gambling if you are just going after money. If you are going to do a startup, do it for the experience, and for the act of creation, but not to get rich.
Not having a degree, you are going to get yourself into a tough situation though. If you ever decide to get a job at an established company, you'll face a couple of things: first, HR will probably throw out your resume, and even when you get interviews, chances are your knowledge won't align with what they are testing for (algorithms, mostly). Plus you might run into the issue of investors not taking you seriously.
Certainly school will always be there - you won't ruin your life by not going back right away. Yet I think these are all important things to consider.