My DH voted for Trump because he wanted a president who would "drain the swamp." Clearly, as Fox commentator Neil Caputo said, "How can you [Trump] drain the swamp if you’re the one that keeps muddying the water?”
It seems Bernie is not completely out of the question for a 2020 run, especially since his nemesis Hillary is out of the picture. I think that there's a lot of crossover between people inclined to vote for Bernie vs Trump, despite the huge ideology gap. People are sick of business-as-usual in Washington, and they thought Trump would deliver. If people could understand that Bernie is not a Communist, but a man of the people who can lead in innovative ways (the growth of Burlington VT attests to that), he could actually do pretty well in 2020, in spite of his age.