BIL: Happened on your post in this forum. I'm 12-stepping in Alanon/Naranon so usually don't end up in this forum. But here goes.
Get yourself into Alanon/Naranon. This thing with your brother is complicated. It has taken years to get to this point; hence, there is no quick fix here. Going to Alanan/Naranon will get you to the point where you can work through your strong emotions and can then begin to ask and find answers to the question of "Whose problem is it to solve?"
Whose problem is it to solve that your brother bums money from your parents?
Whose problem is it to solve that your brother smokes marijuana?
Whose problem is it to solve that your brother smokes marijuana in your parent's home?
Whose problem is it to solve that marijuana smoke bothers your eyes?
Whose problem is it to solve that you are exposed to your brother's lifestyle?
Whose problem is it to solve that your brother does not work?
Whose problem is it to solve that your brother's behavior negatively impacts holidays?
You gristle at the idea that the solutions to some of these problems involves action on your part while having to leave some of the other problems to be solved by other people (which may never happen). That's where your willingness to be exposed to the wisdom of other people (in Alanan/Naranon) will help you tremendously.
I do hope you do that. It really is the best gift you can give yourself and your family.