zero-sum
adjective [ before noun ] uk/ˌzɪə.rəʊˈsʌm/ us/ˌzɪr.oʊˈsʌm/
一方得益一方受损的；得失所系的
used to refer to a situation in which any win by one person always means a loss to another person involved
The stock market is now a zero-sum game, in which one party gains what the other loses. 股市现在是一种零和游戏，有人赚就有人赔。