i disagree, and here's why: most of the applications that we see developed are based on ideas that flow from the common experience, then crystallize via a good idea. regardless of how good your idea is someone else is thinking of it too, and it becomes a question of who can get it to market fastest. if you're a part-timer competing with someone who isn't (as i was in a previous project) you're going to ultimately lose, as your potential users will latch on to the thing that fulfills their needs first, even if doesn't do so best. when that happens, your userbase's growth curve will be slowed.

a few months ago i quit my full-time job to pursue a startup with only $6k in the bank. yeah, food is slim pickins, but we launch stage 1 tomorrow and it feels darn good.

none of this is to say you can't take on a few hours/week of contract work of some kind, but your startup should be your primary focus.