When startups die, the official cause of death is always either running out of money or a critical founder bailing. Often the two occur simultaneously. But I think the underlying cause is usually that they’ve become demoralized. You rarely hear of a startup that’s working around the clock doing deals and pumping out new features, and dies because they can’t pay their bills and their ISP unplugs their server.
Startups rarely die in mid keystroke. So keep typing!