"Of course this is assuming you're young/no dependents etc. but that's most startup founders."
This is far from true.
"In fact, research shows that the median age of U.S.-born tech company founders is 39, and there are twice as many entrepreneurs older than 50 than there are younger that age 25." [1]
I wonder if that's because older founders (assuming age = more experienced) are more likely to succeed or last longer than a very young (<25) founder, so they don't go back to normal jobs for longer if at all.
This is far from true.
"In fact, research shows that the median age of U.S.-born tech company founders is 39, and there are twice as many entrepreneurs older than 50 than there are younger that age 25." [1]
[1] http://www.entrepreneur.com/article/242851