Alternative answer: Ensure that the implication that "The IPO" and every individual's "exit" depends on those 80 hours is widely heard and vaguely understood. Hire people who believe that.
If you tie it to an exit, you're setting up for tension. "If we exit, you'll get one hundredth (or even far less!) of the payout that I will, but my payout may be immediate while you're transferred to the acquiring company. Still, I need you to work as hard as I do."