In theory, I agree with you as long as the person is mature enough/adult enough(not 18) to make his own choices and he KNOWS 100% that what he's doing is optional and very dangerous.
Objection your honour!... Go **** yourself im 18

Age holds no bearing though. Some people grasp things well before age 18. Others could live to be 100, and they'll never get it. Though the most stupid tend to live rather short lives anyway.
The best die young gallowmere.... don't make me bring up a list to prove it, it will only make me sad