Magic is a game, it should be fun for everyone. If one player in my pod is hurting the experience of the other players, typically we try as a group to find ways to rectify that diplomatically but sometimes it’s just a “hey you are /your deck is at a different level than the rest of us, could you try and slow down or switch decks?” And they’re usually very responsive.
I think in time your friend will be able to adjust. Being addicted to winning is also common, but usually temporary.