If no one cared about you, then you're not obligated to care for them. It's a natural law. It's the same way that I have lived my life and it's never going to change.
It's very necessary to care about others. It's very necessary to extend some kindness and love towards others because the same thing will be extended to you. You can only stop caring for those that doesn't want or care about you.
With other people don't care about me, then they don't expect me to also care about them. I always return the same energy to anyone that I'm dealing with.
If you care for me, I care for you too. Days are gone when you put yourself in front of the battle ground to be trample when you can stay aside and have your fights. Your energy determines my own towards you too.