Sounds like he is substituting one drug, for another. So goes addiction.
Too bad someone allows an able 34 year old, to live at home, like a big ole baby, without a care in the world. So goes enabling.
You can either make it your problem, or not. Regardless of what you do, or not, your brother is going to do what he wants to do.
Take the focus off your brother. You will sleep better, at night.