Women can be sexist against their own gender; people can (and do) vote against their own class interests; racial minorities can take the side of their oppressors.
Complex reasons why -- people prioritize other aspects of their identity, the big one in the case of conservatives seems to be being evangelical Christian and swallowing the hard-right belief system that tends to go hand-in-hand with that description these days.
But anywho, in this case your meme is a giant red herring as photos of the Trump riot show it was 99%+ white.