Socialism depends on everyone doing relatively equal work, which is absolutely not the case in American.
In an ideal world, socialism would certainly work. When I was a teenager, I talked about socialism being a wise system...as I got to understand people and the world, I see that pure socialism would be extremely unfair.
Pure capitalism is also not ideal because there are very greedy people.
So, like most other things in life, a compromise and combination is probably best.