My boyfriend is mean to me when he’s drunk

Is there anything I can do to stop this or make him not mean? I’ve already tried being extremely polite and agreeable when he’s drunk and it doesn’t work. Also how much of an idiot am I for staying with him after realizing this? Also he doesn’t drink often at all, but it seems like when he starts drinking he just can’t stop? Like he can’t just have two. How much of a red flag is that?