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.
The flaw in capitalism and the flaw that makes it unmanageable is how over time capitalism will find ways to extract more for less.
This will always fall to the workers. The recent recession had tax payers bail out the banks as well as pay bonuses. all because banks got very greedy.
I think the flaw is human nature. All governments and organizations are corrupt. All implementations are always twisted to suit the greed of individuals.
It's entirely possible to create policy and enforcement mechanisms that would mitigate or eliminate excessive greed but nobody with anything votes for it because they'll lose out on their own personal greed by their measure. They want that chance to fleece the masses even if they aren't in the club that's already doing it.
People blame capitalism, but capitalism isn't the problem. The problem, as always, is power.
Under feudalism things were much worse. Serfs worked 6 days a week, 12+ hours a day. Up to 3 days of that week was spent tending your lord's lands for free.
Under absolute monarchies, dictatorships and police states you work as hard as you can for whatever hours your employer sets, and you keep any complaints to yourself or you're dragged off to a camp, or summarily executed.
So far, every time "communism" has been tried, it was just a dictatorship or police state where the leaders pretend that there's a higher ideal.
Capitalist republics don't give people at the bottom much power, but they get a little bit. And, that little bit is the best that the people at the bottom have ever had, even if it isn't much.
The fact that there are people at the bottom isn't the fault of some political system, and especially isn't the fault of capitalism, it's the fault of human nature.
Blaming "capitalism" for all of society's problems is about as useful as blaming God or some gremlins. For example, if you're in the USA and you blame "capitalism" for your problems, then what are you gonna do about it? There is no path to change this society from capitalism to socialism or communism. We have entire armies of military and police who will ensure that the status quo stays in place. You also can't vote your way out of this. No candidates advocating such changes will be elected.
The best thing we can do is aim for better regulation of the systems that have allowed for the oligarchy to take it all over. Which won't be easy or quick at all but is at least somewhat possible.