Well, you've done the neighborly thing and talked to her about it personally. She seems totally unconcerned that she and her roommates are breaking the law. Regardless of anyone's stance on the legality of marijuana, it is currently legal. Definitely complain to the landlord. You shouldn't have to put up with that. I'm sorry her response to you doesn't sound to me like she has any real plans to change. If she gets evicted or arrested, that's not really your problem. You could have always called the cops instead.

PS
She's totally wrong about everybody smoking pot. Loads of people don't. Probably well more than half of the residents of your complex don't. Most likely even more than that.