Or does he basically rob you?
Sometimes a Farmer will show up and ask for money. This will happen from time to time and if the player lets all the farmers have money, they will eventually hold a festival to celebrate and give the player rare gifts.
-Bulbapedia
So basically he does not rob you.He will give you rare gifts if you let all the farmers have money.I dont know what are the rare gifts.Sorry
Hope this helps!