zero-sum bias

is a general belief that social relations are inherently antagonistic such that one person's winning makes others the losers, and vice versa.

A general belief system about the antagonistic nature of social relations, shared by people in a society or culture and based on the implicit assumption that a finite amount of goods exist in the world, in which one person's winning makes others the losers, and vice versa [. . . ] a relatively permanent and general conviction that social relations are like a zero-sum game. People who share this conviction believe that success, especially economic success, is possible only at the expense of other people's failures.' (pps. 526-528).[2]

is the tendency to perceive a situation to be such that one person gains at the expense of another.

Zero-sum bias is the tendency to perceive a situation to be like a zero-sum game (i.e., one person gains at the expense of another).

zero sum bias, n.All

zero sum bias