Capitalism is a system that allows people to make wealth based on trade. The winners in this game are the people at the top of the hierarchy. All these type A billionaires are the ultimate winners of the game. Zuck is a winner.
In communism the system says there are no winners. Everything needs to be fair.
There's plenty of exceptions. PR China just after Deng was a good exception, and so was the Soviet Union after Stalin.
But they were only exception in the lame technical sense that you didn't have a single 'guy at the top' in charge, but a sharing of power by eg something like the Politburo.
Have you ever seen a succession struggle in eg any old monarchy?