Honestly I'd just give him whatever he wants. Bear with me for a second. I know some kinds of people who are really needy and demanding like this. One guy kept asking for specific magic items, and threw a fit when I didn't give them anything special. Eventually, I got so annoyed that I just gave him the item. After that point, I just gave him every single thing he asked for. He was really confused at first, excited for a while, and quickly grew bored of it. He lashed out at me, assuming I was giving him cursed items or something. In reality, I was just giving him what he asked for. It took out all the challenge from the game. He ended up quitting after a few more games. Not saying this will work for you, but something similar might. Give him cursed items that do what he wants, but then has some negative effect. Or make it so rumors spread of a weak forest weirdo with a crapload of magical loot, and send loads of bandits after him. Specifically him. Set up a caravan raid, have enemies constantly trying to steal from him. That's one way to do it if you want to attempt to solve the problem in game. You might want to explain it to your other players beforehand so they don't get jealous or think you're pandering to him simply because he's complaining a lot.