They hate because they’ve been brainwashed, and because the left is a cult.
Old fashioned hatred by the left festered in the south when they were the owners of slaves and continued through the days of their Jim Crow and KKK. Modern day political hatred by the left came with the Russian Revolution in October,1917 with it’s associated violence and suppresion of individual freedoms.
I don’t think those ideas dig deep enough. Those aren’t really root causes.