Answering my own question, in the US, the last reasonable argument I heard (I've lost the link) computed about $4 million as a reasonable amount to shoot for if you want to retire early into a relatively modest middle-class lifestyle that's not luxurious, but not minimalist-survivalism either, and don't want to have to think too hard about how to manage your money/investments.

I don't know how those calculations would change given the current prospects of the stock market.

I've concluded the Tim Ferriss type model (based on passive income streams, "mini-retirements" instead of early retirement, aiming for low rather than no work, etc.) is not really workable for most people. Going for the big capital stash, via joining a startup with good prospects sufficiently early, or working for some evil corner of Wall Street for a few years, is still the better route to financial independence.

I posted the question because I haven't heard much new talk of F___ You money that takes the post-2008 financial crisis into account. I want to know how thinking has changed.