Capitalism rewards exploitation.
You've probably heard "There is no ethical consumption under capitalism" - and historically speaking, and in my experience, this holds to be true. I couldn't be typing this on my glass god rectangle if there weren't some children in a cobalt mine somewhere - at some rung on the ladder, people are dying, because where's the incentive to lift others out of poverty? Why would any capitalist elevate their source of cheap labour and materials out of the blood and sand?
There's also the interaction we have between the capitalist and socialist aspects of our society - for instance nationalised healthcare cannot be administered by capitalists because there is no incentive for the system to function for the good of the patients, but eventually the system will be optimised out of existence (by which I mean, broken into smaller units for budgetary reasons, small units degraded continually until they are canned, and the whole system is sunset because of "sound economic decisions").
Capitalism is the antithesis of what I think any reasonable person wants in society save for those with an amount of blood on their hands. Capitalism is a Mad Max dystopia where a handful of people live as deities whilst the rest of us kill each other in the streets for scraps.
Capitalism might have seemed viable when everyone was suffering from lead poisoning, but it's killing us today, and I support any means to remove this cancer and push for a more equitable life for everyone.
Fun fact - those are not entirely unrelated entities.