You are really the only person who can answer why. Is there something in particular that you are angry about? When there are so many people you feel hatred for, it seems most likely that it really isn't them, but something that is going on within you. Maybe it isn't even them that you hate, but rather yourself? Do you hate yourself? Or rather, do you love yourself? If you aren't able to feel love for yourself, you can't really love anybody.

Do you have a therapist? With the intensity of negative emotions that you seem to have, I wonder what trauma you have been through and what else might be at the bottom of it. You can get some support here, but if you want to create a better life for yourself, it would really help to have an organized plan working with a therapist to really figure out what you want and how to get there. It won't be easy, but the way that you are living isn't easy either.