There are ENDLESS dangers of letting your kids be on the internet without supervision.
Sure, you did dumb things as a kid, so did I. Our parents didn't know where we were or what we were doing lots of time!
Those days are gone. We didn't have bad actors telling us what would be "cool" or "fun" to try knowing they could harm us.
We didn't have predators literally on a screen in front of us talking to us!
Monitor your kids.