Go talk to them, listen to them, sympathize with them, you know, be a compassionate human instead insinuating their stupidity by outright calling someone they support stupid.
I joined a big discussion group to see how I could convince people ( > 8000 Dutch members on Facebook).
While I took a lot of effort for 5 months to reason with the outliers of the group.
I had concluded that it was not possible to reason with outliers since they used "Whataboutisme" and the only effective way to convince other people and "shut them up" ( I know it sounds rude) was to actually be rude, handle their current arguments and point out the idiocracy of the arguments they were using ( hence the harsh term used).
My effectiveness rate went from 4-5% to almost 90% in having the "last" argument. It also seemed to greatly reduced the amount of pointless topics started by that person.
There was only once someone effective in working arround it, using "doubtful" sources.
Who can't see that Tr. is in politics for his own pockets is it too.
I've added a lot of pointers already. But another one is to look up the documentary about his son in law: Kusher Properties.
They are literally made for each other and not in a good way.