That's partially because like many other words and names (just consider Isis, an important goddess of ancient egypt), "socialism" to most people means the type of absolute control that communist countries usually feature. But of course, as a word/concept, socialism is just the application of socialist policies, not even remotely alluding to some absolute end goal or so. And naturally as a part of society except a tiny minority at the top, most people would benefit from more socialist policies.

Survivors bias. People in Russia or China don't appear to complain about their systems because... they can't.

No, everyone doesn't hate capitalism.