Could also be summed up as: Don't be a dick lol

I used to be like this in my previous life that shames me to think about. I hated myself and my own shortcomings so I wanted to spread that hate to others. It was a sort of "Oh you're successful and happy? Well I'm not so I'm gonna shit on you" Yeesh it drives a nail into my heart whenever I think about it. I like to think that I'm a much better person now but whew what a horrible person I used to be~

"Do to OTHERS as you want them to do to YOU."

That was what my parents always told me growing up. Sadly we live in a world where not everyone was told that or even cares. The best thing I've ever heard to deal with this reality is: "Don't take criticism from someone you wouldn't go to for advice". I'm not trying to discount anything you're saying because I agree, it's just that you're always going to run into rude or inconsiderate people.