Why there are parents who look at their children as merely investments?

I was disturbed recently when I heard my neighborhood nagging and says nasty things to her children. She is a mother with seven children, all of them already have their own family.

I heard her say to them, "You forget how i suffered just to raise you! You still have an obligation to follow and do what i tell you even if you already have your own family. I am still your mother and you owe me your entire life. You must give back what I did for you."

I feel sad about this, because I am a mother too, but I am not favorable with what she said.

I don't believe we raise children so that one day we will force them to pay what we did for them. Besides, it's not their choice that we became their parents. It's our responsibility as worthy care-takers to nourish those lives lent to us by our Creator. Why there are parents who look at their children as merely investments?