THAT'S THE POST.
Every human instinctly knows that a very small minority living in unlimited luxury while half the world lives in squalor is an unforgivable evil that can't be forgiven.
Theory is cool and good, and you should study it as much as you're able to, but at the end of the day, you don't need to read any theory at all to understand why this is wrong. You just need the basic human empathy we're all born with.
A significant amount of people enjoy being one the priviliged few and have no sympathy for those screwed over. They still KNOW it's morally wrong, they just enjoy it. Most people don't think like that though, and have just been conditiond since childhood into believing contrived justifications of why it has to be this way or why change is dangerous if not outright impossible. In my experience, they all know the current capitalist system is unacceptable if you press them enough, even if they'd never use those words or think about it in those terms. It's just that none of us know what to do about it.
The entire point of both modern political and economic theory is to justify something we all intuitively understand isn't okay, which is probably part of why modern society is so fucked.
A lot of people aren't going to intrinsically view captialism as wrong if they're on its good side. They'll automatically conjure its defense into existence by sheer refusal to view themselves as bad peoole because of their status. That's where you get all the stories of self made millionaires or the risk of being a business owner, or any number of bigotries or raw hatred of the homeless.
My cousin is a small business dipshit in a small town. Complete reactionary and goes to a cultish evangelical church that teaches prosperity gospel. He's never going to view his business as exploitation no matter how it's explained unless he's humiliated onto the other side of it...and probably re-educated with theory.
Sorry about your cousing. People will latch onto the wildest shit to justify their own privileges.