In a “zero sum game” (ZSG) one side must lose, in order for the other side to win. In life you often find people who every interaction as a ZSG.
I remember when the essence of being a Liberal, was the core belief that in situations you should always strive for a win-win solution. Then came the Leftists.
The core belief of the left, is that the other side cannot win. It must be utterly vanquished, completely destroyed. Everything, every situation, is played as a ZSG.
“Liberals” still exist, but they no longer have power. They feel good about their principles, “virtue signalling”, but they don’t influence decisions made in society. They aren’t capable of changing the direction society is marching in.
Liberals are the warm, fuzzy face of the hard core left. I guess that’s why Lenin referred to them as “useful idiots”.
Historical references
The BBC documentary podcast “Useful Idiots”. https://www.bbc.co.uk/programmes/p008vd41