But, the one difference I'd call out with doing a startup (or owning any small business), is that you're responsible for whether that business fails or not and any of the jobs that are attached to it.

So you feel an intense responsibility to those other coworkers and their families.

You also have this if you're a manager in a larger company, but I think the intensity with which you feel it is a lesser degree (you messing up is still not good, but the company may still survive).