Heh, ancient Egyptians used to take Cocaine, which goes a long way to explaining the Sphinx.
Thing is, when you are young, you WILL try to experience as much as possible, that's, in a way, what being young is for, to practice making your mistakes and making sure you don't repeat them when you are less resilient. So no, I don't think young people who take drugs are stupid or anything, merely young. I was part of the drug culture at 18ish, but I grew out of it. That's normal and natural.
Kudos to you who avoid drugs though, a lot of it is based on peer pressure, so it depends on your environment, and it takes a strong will, particuarly in a teenager, to say no when all your mates are doing it.