[fouc]

It's also more than just math, there's the psychological side of money & investing. When even taxi drivers start giving out stock tips, how obvious it is that it's time to sell? ;)

Some of the other examples from those letters gave advice (paraphrasing here) like:

- If you can't understand what you're investing in, don't.

- If Alan Greenspan or other experts are not explaining economic concepts clearly, there's probably an ulterior motive.

One bit of advice that I think is pretty critical, that most people are missing is:

Don't live beyond or even at your means. For each dollar you make, you don't need to spend that dollar. Consider a 50% savings rate, or if you can't do that, then 20%.