yes, I had similar lessons years ago with options, forex etc. (ok, yes... I needed more than one lesson :D) However, since I am a person that likes to "risk" their well-earned money, I think it's good that I have burnt my fingers early when I had less money. Now I have learnt that at the very least I should not put all my money into one bag. That's the biggest lesson: Split your investments. Split your accounts even. It doesn't rescue all your investments in a downturn but at least you'll likely never lose more than 50%.