This point, which I fully agree, seems to generate a lot of comments. When he landed on Gibraltar in 71, Tariq ibn Ziyad (http://en.wikipedia.org/wiki/Tariq_ibn_Ziyad) immediately burned his ships and gave a speech to his men starting with: "Oh my warriors, whither would you flee? Behind you is the sea, before you, the enemy. You have left now only the hope of your courage and your constancy." The point is, if you don't have this sort of desperate courage, most probably your startup won't succeed. And you cannot do that while holding on to your day job and salary.