I think you know why. Is this a real question or are you just fishing?

Lack of successful alternatives? It's easy to find flaws with capitalism but every other system has its share of problems too.

Brainwashed since birth. GI Joe had the American Express slogan in an episode ("never leave home without it."). Alvin and the Chipmunks had a story about the Berlin Wall propagandizing communism. All the bad guys in Cobra have accents.

This shit is vile and it was on my morning cartoons.

Stockholm syndrome

Often because they're profiting from it themselves.

Living in denial is easy to continue doing and widely encouraged, while being very hard to overcome.

what if it was me

Interesting question. I don't think I've ever defended either. I've also only lived in capitalist countries, so I have no personal experience with other economic systems.

ITT: A lot of people answering for people who have diametrically opposed views to them.