There's nothing magical about startup founders, nor anything to suggest they're any better about figuring out the right number of hours to work than the rest of the world.
Nor are their incentives necessarily aligned properly - if you assume a startup founder is trying to start a business that will make them wealthy, then they may be operating under the assumption that more hours now == fewer later. So a founder may happily push themselves to pull 80 hour weeks thinking that a few years of that pace will pay off so they can coast later.
Most startups fail, and I'd imagine most founders ultimately wind up working for other people. So they'll never get back that additional time + they'll have to keep putting in hours on someone else's behalf.
Nor are their incentives necessarily aligned properly - if you assume a startup founder is trying to start a business that will make them wealthy, then they may be operating under the assumption that more hours now == fewer later. So a founder may happily push themselves to pull 80 hour weeks thinking that a few years of that pace will pay off so they can coast later.
Most startups fail, and I'd imagine most founders ultimately wind up working for other people. So they'll never get back that additional time + they'll have to keep putting in hours on someone else's behalf.