About once every 2 months I forget how to operate a door. I put my hand on the door handle, push, and walk right into the door, because I forgot to twist the handle. That's a monumentally stupid thing to do, but I don't think it necessarily means that I'm monumentally stupid (at least I hope it doesn't :).

I'd be interested to hear why you think every evil person's actions are dumb when evaluated in the long term.