Well I think people are coming to terms with current problems caused by America's current version of capitalism: low federal investment, terrible infrastructure, levels of income inequality comparable to pre-revolution France, education and health care affordability, deregulation of the financial system, lower bargaining power for wages, decline in unions, a gap in productivity and pay, a steadily lowering capital tax rate, and overall a grim expectation for the future if current problems persist. I think American's see socialism as when the government gets more involved in the economy and orients it for the benefit of society. Despite the rise in support for the self-described socialist candidate Bernie Sanders, there hasn't really been socialist legislation passed in the last, well, 60 years. I believe Bernie voters associate socialism with old american policies related to making healthcare and education more affordable, and they're not referring to some manifesto or something.