I think this can be generalized to say that start-ups have a different cost-benefit analysis - one where losses are capped at the (relatively small) value of the company. On the other hand, large companies have to be risk-averse because the worst-case is several magnitudes worse. When you're working at ConEd or AIG, the "tiny probability/worst-case-loss" factors start to matter, because "worst-case" can include investors losing life savings, federal investigations, and jail time for your boss's boss.