People thought Hitler was a joke too.
And Lenin.
Until they got in control and put their madness into action.
Ask the folks who dissented.
Oh... wait a minute... they all got murdered. Never mind.
Americans have little first hand experience of socialism/communism. Both sound good in theory. Every one is equal, guaranteed jobs blah blah blah. In practice it does not work because it goes against human mentality. Humans are by nature lazy. They work only because they need the money. Very few would work if there was no reward.
In summary, we may end up likes of Bernie becoming president and actually experience the bad effects of socialism before Americans learn and reverse course.
That is what has happened in eastern Europe, and even China & Russia who both have a form of capitalism in place now. China created more millionaires in 2019 than United States.