Children badly need instruction, guidance, and correction. But they also need to be unconditionally loved as we teach them, and we don't know how to do that. Imagine that I charge into the room and begin yelling at you because you didn't do something I wanted. I'm obviously angry at you. My anger declares with no doubt that my concern is for what I want, and it communicates to you that what you want matters relatively little to me.
Anger is always selfish.
That is how our children feel every time we're disappointed and angry at them. They feel unloved, disconnected, alone, and miserable. It doesn't matter that we give them cars, clothes, cell phones, and money. It doesn't even matter how much time we spend with them. It's those moments of disappointment and anger that are killing our children.