I just got back from two weeks off of my PhD studies due to burnout, and did some serious thinking about quitting in favor of entering the small business and/or startup world because I still felt burned out. I realized that we've got some projects in flight that aren't finished and that I want to see through, because I stand to improve my reputation considerably if things go well, but if I leave now, I'm throwing out all the investment in those projects to this point.