We are socially competitive animals, just as you can observe in other evolutionarily programmed creatures. We compare ourselves to others, we want to impress mates, etc.
Equality of economic outcome regardless of effort goes against that, which is probably necessary on a planet of finite resources and the scale of our waste, but it does go against that large aspect of our nature.
For the record, I’m probably closer to you ideologically than you think. I think unfettered capitalism does more damage to humanity and the planet than communism ever could, but if you think communism lacks any drawbacks and is perfect, you are mistaken.
There is no such thing as perfection, especially any construct made by mankind. That’s coming from someone who is all for going Old School French on Wall Street and socializing entire economic sectors for the good of the citizenry.