I think what most people are really against is the one way street that capitalism established. It's a broken system, and it wouldn't matter if we had any other system as long as it would still be broken and abused.
On a global level, there are tax loopholes that allow multi billion corporations and individuals to pay essentially no taxes. This money is then used to further enrich the same parties through a financial market that is equally broken.
It has nothing to do with capitalism that wealth is created without a flow of goods or other value that is created from it. All it does is devalue all other wealth at a growing pace.
Capitalism is not ideal, it won't be. But if we moved towards actual, functional capitalism where governments did their part in keeping the whole thing from turning into a one way street, we would have a long way to go before we needed something else.