Ok, that sounds fair. Two hours is indeed not sustainable except in sprints. Though I've known spooky people who seem to be able to get by with not much more than that on a sustained basis.
Yes, but these people are (physiologically) the exception not the rule (this characteristic is not uncommon for sailors, for some types of race sailing it's pretty much a base requirement).
Studies show that chronic lack of sleep is equivalent of being drunk when driving. Do we really want the cognitive equivalent of drunk workers "changing the world"?
On the other hand, don't completely discount the possibility that some of the people you know have access to amphetamine. Careful use can sustain performance for weeks before tolerance sets in.
Amphetamine abuse shows up a lot in all the places you'd expect -- athletes, military personnel, emergency services and hospital workers, even lawyers. With the pressure to perform, it wouldn't surprise me if it's a quiet problem in startups, too, especially since drug testing is pretty much anathema to the culture.