who's leaving a PhD program for a startup? how did you come to your decision?

Also, by no means should anyone listen to me, but if your PhD environment (e.g. Stanford or in a top tech program), personally I would at least attend a semester -- at the very least make some connections.

And if you're like me and being paid to go to graduate school it's more tempting to stick around (especially if other people's research depends on you or you have a general feeling that you're letting down people, e.g. profs that you got you where you are now). There were times I wavered because of this but at some point I told/convinced myself that 10 years from now these people will understand.

People not in the situation tend to be very gung-ho and tell you things like ... do what your heart feels! seize the day! blah blah blah. I've heard it all.

Yea, if only they were in your shoes.

I'm in the middle of attempting to do a PhD and a startup at the same time but it's damn hard. I basically don't sleep. Meeting with my co-founder has become sparse as my research demands increase and it's really affecting our progress -- especially since I'm the coder. In short, if I want this to succeed, I have to leave, which basically I've decided to do at the end of this semester.