This looks like it's a very narrow set of companies. We should be looking back farther, and wider. Recall that, for example, Netscape IPO'ed after 18 months and Amazon IPO'ed after 3 years. For better or for worse, 90's companies generally IPO'ed much quicker than the SaaS cohorts mentioned in the data you linked to. Back then, 10+ year timespans until IPO were rare.
Netscale and Amazon are only anecdotes and pure exceptions of the dot.com era. The set of companies that went burst during this period because of bad management is composed of at least 15 publicly traded companies. If your compensation included shares of any of these quick IPOs (AOL, Yahoo, pets.com, Global Crossing, etc.) your shares would have ultimately be zero as well (compounding interest is what makes you wealthy with these long-term horizon packages and you wouldn't have sold all your shares at ipo).
And whether a company goes bust post IPO isn't really the issue here since liquidity is what we're discussing.