There are two groups of people:
Those that think there are two groups of people, and those that don't.
The premise that socialism is better relies on the government not becoming corrupt. When it fails, it's really bad.
Capitalism also functions great when the government isn't corrupt ... it gives consumers choice and fails much more softly.
If you look at examples of cooperatives, socialist utopia projects, etc.. they break down much for the same reason capitalism has broken down for the majority of people in the US... The largest party is the party that doesn't vote, and of those that vote half of them don't know what they're voting for, and of those that know what they're voting for half of them are basing their votes on misinformation.
Managing society takes work from everybody in society. There's no easy button that keeps the train on the tracks.
To be fair, you did qualify "as it exists today" and that makes a difference. However, the point is it's not capitalism that failed us, in many ways it's ourselves, our parents, and/or our grandparents not paying attention and elected the right people. Similarly those same people buy the cheapest thing in Walmart and don't stop to ask themselves why it's so cheap.
Union busting, the manufacturing exodus, etc, it all could've been stopped if people had just paid more attention. You'll never get me to trust that by moving to socialism as an economic model people are suddenly going to pay more attention and not fuck it up.