Because the leftists have managed to successfully tell the lie that the current ills which have been caused by socialism are in fact the fault of capitalism and free-market economics.
For example, a lot of young people find themselves being ground down economically by huge student loan debt - debt that cannot be discharged in bankruptcy, unlike just about any other debt, including tax debt - but that debt didn't arise because of free-market economics in higher education, but because of the socialist push to give student loans to everyone, and the fact that "free" student loans - loans that no free market lender would have granted without the government's socialist backing - have allowed the socialists in universities to run up tuition costs way ahead of the rate of inflation.
That is, unfortunately, what happens with most socialist policies - the early failures are incorrectly blamed on things that did not cause them, and the call is for more socialism to "fix" the problems the first rounds of socialism caused. Around and around until the economy collapses, in which we either get lucky and have someone like Margaret Thatcher who helps the country to start shedding its socialism, or else we get a full leftist tyranny.