Well, if Mr Gates charges me 500 rather than 400 then well his gain is my loss. So too if he pays me 11k rather than 12k, keeping that extra k as profit for him

Well, if Mr Gates charges me 500 rather than 400 then well his gain is my loss. So too if he pays me 11k rather than 12k, keeping that extra k as profit for himself, his gain is my loss.