To be honest, that is spectacularly illogical. Observing all of humanity in balance, I see not nearly enough grounds for disgust, loathing, contempt, animosity, bitterness, revulsion, abhorrence, enmity, or outright hostility. One particular problem is the superiority you exhibit, especially in your disgust, contempt, and revulsion. It's an unhealthy way of thinking.
But who am I to speak of a logical and healthy mind? I have spent a large chunk of my life with a very unhealthy mind that was incredibly illogical and bubbling with hatred. Not directed, like yours is, just blank hatred - which, when not turned on anything external, often turned on myself.
It's good that you confess it as a problem. If you'd come here and said "Why is humanity so hateable?" I'd say you're a douche and you need to rethink your opinion of the world. But I think you are right to acknowledge it as a problem, and that's the first step to solving it.
I'll suggest a few ideas. I have no professional qualifications but I do have some experience in cognitive behavioural therapy - that is, actively changing the way you think.
1) Think hard. Try to apply a bit of logic. Firstly, what's the point of hating 7 billion people? You'll never meet more than a few thousand and never know more than a few hundred. Even if you could meet them all, what would you do to them? Someone wise once said something like "Hating a person is like taking poison and expecting them to die". Your hatred is harming you far more than it harms them. Try hard to let go of your hate. Leave cynicism outside. Relax. Think about other things.
2) Do you have any close friends? A friend can reaffirm your faith in humanity. I know that friends are pretty much the number one thing to keep me out of depression. A friend can help to lighten your mood, and show you that people can be good, and nice. And also that doing good things with good people is more fun and productive than hating everyone. Also, you can tell your friend that you have a problem with hatred, and they can help you get over it.