In another thread I talked about growing up Catholic and in the process "learning" that Paganism is equivalent to devil worship.
Years later I learned the truth about the Pagan belief and it was almost the complete opposite of what I had grown up to believe. Had I not been open to accepting the truth, it would have been a lot of work to deprogram myself and allow the new, and correct, definition of Paganism to become part of my accepted knowledge.
So when I say, for many, letting go of their hatred is a lot of work, I'm talking about the process of 1) ignoring the BS, 2) deprogramming yourself from the conditioning that led to hating and 3) educating yourself with the truth. That can require a lot of time and effort. And if you haven't had a life changing experience, such as suddenly being the target of bigotry (like what happens to many of us when we transition), there really isn't a lot of motivation to put in that work.
Why? It doesn't concern me.