I have to agree, yurishimo's assumption of returns is wildly optimistic.

At a more sane expected return of 5% annually, you get $50k a year to live off of to just keep what you have (or rather, watch it slowly erode in value due to inflation).

That is basically a one person income, maybe two adults if you pinch pennies and live in a crappy apartment or a low-end house in a midwestern suburb.

You can get a lot more lucky with a million bucks than you can with 10k if you gamble, but there are no guarantees. Risk tolerance is the most impactful variable. For those in the low risk tolerance group, I think you'd need at least 2 mil these days. And that's with being frugal, as well as probably not having much left over for kids.