Good news folks. Its possible to get rich through hard work and a little cleverness. That's also the bad news.
PS: Rich means "Possessing great material wealth" which I think it stands for more than just the ability to support an upper middle class lifestyle without working.
To sustain a flamboyantly "rich" lifestyle on investments alone, the lower limit of necessary wealth is probably more like $30-$50M. That's, of course, significantly harder to achieve (Wikipedia says 95k people worldwide are this wealthy). In fact, the groups of people I can think of who are typically associated with such flamboyant lifestyles (Fortune 500 execs, financiers, entertainment icons) do not, as a rule, do so based on their investments alone - rather they continue to work and are merely paid large salaries.
I guess it just reaffirms the pg/yc philosophy.