I get what your saying, because it does say in the lyrics that he made a decision to do it.
I think sometimes people either try it out of curiosity or they come to it from another drug, like a gateway drug.
Meth and Heroin are a real problem in the city I'm from and it's sad to see what it does not only to the people themselves, but to their families. 4 blocks down from my house the cops busted a meth house and 3 adults and 2 children were removed. They had a meth lab in the basement. I feel very sad for those kids. Sorry to get so serious, but this is an issue very close to home.