It's a freely made personal choice.
Just like the gangsters choose to mow people down in the streets. It's their freely made choice. At least the addicts are only hurting themselves.
It's even stupider for drug dealers to blame drug users for their own addiction to violence and money. Mexico is actually trying to blame drug users in the USA --- not that they don't have plenty of their own drug users to blame --- for the violence that is destroying Mexico. Blame it on the pot head, the extremely violent Mexicans certainly are not to blame for anything.