When I think of "stupid" things I did, I very quickly move to "insane" things I've done. And there were plenty.
In fact, I wouldn't feel comfortable listing all my actions.
But I will list one that should show you just how thoughtless I was:
I was running with this addict. He was a fugitive, wanted felon and completely addicted to drugs, booze and the lifestyle. I let him stay at my place, while I left to run errands. I was shocked upon arriving home to find all my jewelry and cash was gone, and so was he. The stupid part, on looking back, is that I was "shocked."