I know some folks (can think of one couple in particular) who retired in 1999/2000, but severe hits to their portfolio in 2002 and returned to work in 2003. I think these folks had a) never heard of the 4% rule and b) were mostly invested in high-flying growth stocks. Many, many folks today still think you can retire and expect to pull 8 to 10% out of your portfolio and do OK. Many, many folks don't understand about diversification, asset allocation, etc., either. It's amazing. Anyway - the good news is that these poor folks seem to have put their financial house back in order and are retiring again.
Gosh - so many folks see to get the WORST advice from financial advisors. Such a ripoff, in SO many ways.....
I know of one guy who retired in his 40s. In spite of having an apartment in Paris, and traveling between the US and Paris doing all sorts of cool stuff, he got bored and somewhat depressed without a job. He went into a political consulting/attorney type position for the Texas senate and seems to be much happier now than when he was retired. He is still financially independent. He truly believes that one cannot be happy without some type of job.
Audrey