Once again, it helps to have a historical perspective. For many decades, Americans relied on individual households, family members, and close friends to get by. The nation provided very little to the well being of the individual, and people either made it, or didn't make it, based on the resources they had immediately available to them.
Communism/Marxism becomes a reality in 1917, and shortly thereafter Communists start to appear in the United States and Great Britain. Who are the first Americans attacted to Communism? Mainly the well-to-do Ivy League/Cambridge liberal types, who have been raised by wealthy families and who have wanted for nothing. They have no real clue as to what it takes to really make it in the World as they have been handed everything. So either out of ignorance, guilt, or both, they see Communism as a means of making everyone equal. After all... if they were given everything by their parents, why not spread the wealth around to everyone. It would be utopia!
Life under Lenin wasn't ideal, but to these young entitled folks, Communism looks pretty good. Many of these folks are destined to bigger and better things, like politics, and before you know it you have Communist supporters advising the White House, State Department, etc. It isn't until Stalin's purges and other excesses in Europe that Americans as a whole start to view Communism as an evil. To many American Communists, Communism itself is a great thing, it's the execution of it by the Soviets that's bad.
Now comes the Cold War, and things are heating up for the Soviets. We've got the bomb, we've got resources, we can take them out. The Soviets need allies in the United States and Britain, and who do they look to? The same idealistic folks who flocked to Communism in the 1920s and 1930s... college students. The Soviets co-opt some of the more impressionable of these folks with talks about worker's rights, the need for equality, the way the Soviets take care of everyone for free (none of which is true, but that's besides the case.) Now a lot of these co-opted college kids in the 1940s and 1950s go onto become college professors (just as they do today), and spread their vision to the kids coming through the schools.
Along comes Vietnam, and the Communists are losing. They need help, so they go back to their friends in the US, and funnel money into front groups that support anti-war efforts. It was no accident that the anti-war movement started at the colleges. This was where most of the communist sympathizers were, and where you could find the largest number of draft-age teens who didn't want to go off to war. While many of these kids had no ideea who they were really working for, or who was paying the bills, many did know it was the Soviet Union. The best money that the Soviet Union ever spent was on funding the anti-war movements in the US.
Now comes modern day America, and Communism is dead and buried for the most part. But now the Liberals who grew up with the "war is Wrong" mentality given to them by the Soviets (which was a true mentality given that the Soviets were losing the war at the time) are now your leading Democratic politicians and college professors. They don't grasp, or don't want to grasp, that they were merely used as tactical weapons by the Soviets against the US. They continue to see all war as bad, and now see Socialism (since Communism stirs ugly images of Soviets) as a means of once again making things fair for everyone.
And who are the kids listening to them? The kids today have it about as easy as the kids of the priviledged had it back in the 1920s and 1930s. Most have a car before they are 16, most have the toys and clothes they want, and most have never had to work for anything. Everything that they have has been given to them by their parents, so what could make more sense than having the government provide you with everything after you move out of your parents's house? They don't see the need to limit socialism until they start working real jobs and start paying real bills, and start hearing about how their taxes are going to go up to support all those poor people on the public dole who are getting the same services that they have to pay for twice (once for themselves and once for the poor.) That's when the change kicks in.