This is a stupid question.
Yes. Because usually when someone does something stupid it's a mistake that they later realize was stupid. Sometimes they are driven by other factors and at the time don't think about what they are doing. People learn from their mistakes, it's the best way to learn.This is a stupid question.
If it only hurts them than yeah.
Yes. Leave them to their stupidity, it will weed out the idiots as they slowly die off from, well, doing stupid things.