We don't pay players to win, we pay them to make their team - their franchise, money. Does winning lead to increased income for a team? Yes, but to a point. Players such as Derrick Rose and Kevin Durant do not have to win in order to make their team money, they simply have to radiate their superstar presence. There are players that are required to win in order to justify their salaries, such as Tim Duncan of the San Antonio Spurs, who do not have a large sphere of media influence but their success props their respective franchises up.
Players are not paid based on their wins added, but the wins they added can correlate with their salary. If a player has a large influence on the media or presence overseas, this is much more valuable to a business (let us not forget, sports teams are in fact businesses) than a winner. If we are overpaying a player then that means we are paying somebody more than they are worth on and off the court.
I don't expect you and other armchair GMs to understand this; there is a reason why I sit in the VIP box with Dr. Buss while you sit in the 4 dollar nosebleed seats (or the 8 dollar frontcourt seats) of your franchise's arena.