When people say "Just don't take it personally!"

I hate when people say this in response to people who behave like assholes to me.

For example, there was a guy who bullied me a lot in my senior year of high school. He was an annoying, spoiled, entitled, popular rich kid. He drove a new white Lexus, lived in a mansion, wore designer clothes, and had parents who let him throw parties regularly. And these were LEGENDARY parties... not that I would know from personal experience because I was never invited, but people wouldn't shut up about them for months after they happened. But he was always just a real asshole to me for no reason. Many of his friends would say to me, "You know, he has a lot of problems in his personal life. I know he can be like that sometimes, but it's not personal."

Umm... okay, first of all, this asshole comes from money, and is way more privileged than 99% of the world's population. So, it's pretty hard to feel sorry for him.

Second, I also have problems in my personal life, but I still treat others with kindness... even when they don't deserve it.

Lastly, considering he treats me a lot worse than he treats others, I think it's safe to say that it's not NOT personal.

Of course, this is just one of many examples. Like when somebody tells you that your crush is out of your league? Or telling you that you will never amount to anything in life? How am I supposed to NOT take those personally?