Socialism is just a word that's used as "not capitalism". The point is, though, if the ownership of capitals (means of production) is so concentrated (1% own 90% of capital), then pretty much the only "solution" is effectively disowning them, consequences be damned. That's clearly in contrast to the spirit (and law) of capitalism, hence many (even capitalists) would simply call it "socialism" (or "communism"), even if it's completely different in the details (e.g. not everyone is paid the same).