Since the US didn’t start sending pros until 1992 it wouldn’t be fair to include players who weren’t eligible. So for the sake of argument let’s say they had to be 30 years old or younger at 1992. So players like Kareem/Wilt/Bill Russell/Jerry West/Elgin Baylor/Bill Walton aren’t applicable.
With those parameters who is the best American player without a gold medal?
Walton’s refusal didn’t cost the US anything. The Soviets won because of corrupt officiating. If Walton had been there, it would have played out differently but the officials would still have ensured a Soviet win
USA would have won if Walton played. He was one of the best players in the world and even with all the corruption the Soviets only won on a miracle of a play.