The founder has likely foregone salary altogether for some time and run up personal debts while doing so. They've probably tipped a lot (relative to their net worth) of initial capital into the company to get it off the ground. If everything goes wrong, they need to go find a job _and_ deal with the mountain of debt they're now in.
If the company is at a stage where it has paid employees, a significant part of the risk of failure has already passed. There's plenty more risk to come, but you cleared the first few hurdles; and they're big ones.
Source: Founder that did all that stuff.