There's almost nothing that can be done in a case of a voter who makes bad decisions. They'd have to learn to live with the consequences caused by their poor decision making. You can show them, you can educate them and you can rationalize with them all day. But, they just have to face the music. Which is what I believe anyone who voted for Trump is going to have to go through. They think voting for him will make their lives better when he's most likely going to make them struggle day after day if not put them out of whatever comfort zone that they once had.
They don't seem to register in their minds that voting for a bad leader is going to affect everyone involved, not just pick and choose what groups of people to affect.
The unfortunate part is someone had mentioned that it is a patience thing and it is all about time. It could be years for them to finally see whatever light there is to see that shine on the errors of their poor decision making. Quite frankly, I do not have all of the time in the world and I don't exactly know how much time I truly do have left, so I just brand them as hopeless and move on.