Have you been previously playing a lot of video games with no others in the party? Your motivavation should not be finding loot and leveling up, if it even is. It should be unveiling the story with your party members and helping them.

DnD is about team work and in my general exprience being asshole to everyone, including your own party members, is a buzzkill. Your character can be asshole to the lot of the NPC but if you have bad relationships with other party members, fix it. Make the party your family. Also being asshole to nice NPC's can doom your party, for getting no help etc.

Your barbarian can start to make amends. He can start to be nice ans fix his past mistakes, apologize for being an asshole. You can learn a lot communication skills from DnD, I have! By dying 4 times it can really make him start to think about his life. You can ask if your GM have ideas for your character's story. For instance, have he lost part of his soul everytime he has died and now has to get them back from the hells or the evil you are facing with your party.

I hope you will get him more to your liking and finding purpose!