I think a lot of Dems voted to keep Trump out of office. I think Trump voters voted for someone who "says it like it is", will "drain the swamp" or wasn't part of the establishment. Sanders had the same populist energy and messaging that Trump had & could've swung it. It's all conjecture though.
And don't forget that quite a few Trump voters were specifically rejecting Hillary! (Sure, some of them would have rejected Bernie too, but I doubt they would have been as numerous.) In elections where people vote for one candidate to defeat the other, the Republicans tend to have the edge...