So this is a bit of a personal thing to write, but:

I might be projecting but I think I get how you're thinking OP, I used to try to understand and make excuses for everyone all the time. I used to try to understand sociopaths in the news or sympathise with people with horrific views because they were outcasts. I used to even try to reach out to them. It turned out that people who've continuously hurt me personally over the years molded me into that way by getting me to sympathise with why they were hurting me.

One of the hardest lessons I've ever had to learn was that it doesn't matter why someone is the way they are, it just matters that they are. If you do something shitty but you do it because of your past or the environment you grew up with, nobody has to stick around and listen to your life story. All that matters is you figure out how to stop.