I guess humans are selfish and all they think about is benefiting themselves. But also, humans' nature is to band together as they need each other to survive. Every day I wake up to a roof above me, to blankets covering my body and clothes sticking to my skin, with the bed keeping me upright and the floor keeping me safe from dirt. All this is made by people I never knew, and I depend on them without realising.
So maybe when people don't save other people, they're afraid themselves.
Maybe you've gone through a society where people only think of themselves, but hopefully as you go along with life you'll see that there are also good people too.
Right now, you can do nothing but be the best person you can be. To be the person you want to live with for the rest of your life. In that way, you can influence not only yourself, but other people around you to be kind too, and that's the best way to kill this selfishness in other people.
It's okay, just hold on. Life is hard, but it isn't so bad. Change whatever you hate about yourself, don't let that bring you down. We don't have to be scarred by cruel reality. We don't have to let it touch what's pure in ourselves. We can stand over it, and we can step over it, and we can overcome it. If you need to talk, I'm here! ^^

They've promised that dream can come true, but forgot to mention that nightmares are dreams, too.