I have a few friends who have worked for startups. Some have hit the stock option jackpot. Others haven't.
The somewhat ironic thing is that the ones who've hit the jackpot have upped their lifestyles accordingly. So I'm not sure if they're in any better shape to retire (in their current lifestyle) than the ones who haven't.
In fact, most of the ones who have hit the jackpot at least once are now at a different startup trying to do it again. Apparently, it's addictive.