Am I wrong to think smoking weed is gross?

So I'm 15 years old and I know way too many people my age smoke weed. Even on tumblr, all the people my age are posting things about weed. People are always ranting about how weed isn't bad, how it should be legal, how it never killed anyone and about all the health benefits blahblah. But I still think that smoking it is disgusting and don't have a clue why teenagers think it's so great. Whenever I try to convince someone how bad it is, I can't because I don't have any good arguments. So, what do you think? Do you think smoking weed is bad or do you think it should be okay for teenagers to be smoking it? Do you look down upon people who do it?