It sounds like you're dealing with someone who is either threatened by you or he is incredibly insecure in his own intelligence (or a combination of both). He is probably not very satisfied in his life, but he has atrophied in his self-growth.
Your manager has probably realized that it isn't worth their time addressing because:
Either way, dealing with a jerk like that sucks, and I'm so sorry you have to. I'm in an incredibly similar situation at work right now with a washed up asshole who speaks down me at every opportunity, especially when our director is around. When I brought it up to manager, she made excuses for him and said she just ignores and avoids him. I brought his behavior up to his manager (our director) and she told me that he is working on himself and that people don't change overnight.
He lost his temper with me in a call recently and I had enough. I told my manager that I could no longer deal with his unprofessionalism. I cancelled my recurring meeting with the jackass and he sent me a condescending email explaining why we did, in fact, have to meet regularly - he even apologized for his tone (but not his words, condescension, etc.). I'm currently considering my next step in this saga, but I've decided to find a new job if I can. It's not worth sticking around a toxic work environment if I can financially afford to leave this job when I have another lined up.
I realize our situations aren't the exact same, but it'd be worth polishing up your resume - at the very least to remind yourself of your own worth and skills. You're handling this like any reasonable person would - confused and frustrated. I'd also suggest trying the "grey rock" method with that jackass. Fade him out and call out his bullshit too if you can. Good luck!!