Misanthropes are a group of people who feel hatred and / or distrust for their fellow humans. And it is with good reason if we look back into atrocities committed in the past, or even the horrible acts of the present, ranging from warfare and murder to rape. It is not that difficult for misanthropes to make their case and defend their views.
Some people hate misanthropes and as such add to the whole chain of hatred. I personally must say I like them; although I am not a misanthrope myself, I can see where they are coming from.
It boils down to how we see and define human nature. We can be like Rousseau and claim that human nature is pure and good and that it is only through contact with filthy corrupt society that we get inverted. Yet we all know that we are not little angels and in fact, society is made up of individuals who lip-sync and go along for the ride.
Thomas Hobbes, on the other hand, has a more pessimistic view of humanity. According to him, we need constant guidance, and laws are there to protect us from doing harm to others. Without laws and moral consequence, all would disintegrate, and we would be robbing and looting everyone else. Something similar like that happens in times of emergency, radical social change, revolution or when your favorite soccer or hockey team loses an important match.
Human nature to Freud is a complicated matter too. We have the id, the pleasure principle, which is merely looking for satisfaction and gratifying desires regardless of its outcome or consequence. We have a sex drive, our libido, and a death drive, the desire for ending life, but also the thrill of destruction. The latter Nietzsche sees actually as beneficial for humanity and a stepping stone towards his desired Übermensch.
All this may be a reason for idealists to reach for an immaterial soul, which is trapped in the body or the sins of the flesh. There seems to be an eternal conflict then between good and evil, and we are caught in the middle. There are bountiful good human acts, but many of them get drowned in acts of evil.
I am obviously not going into details about humanity's capacity of causing pain and destruction. We also mistreat animals and our environment. We do not even value ourselves and become self-destructive in many cases. The misanthrope epidemic might be rising.
All in all, I do not think that misanthropes are evil loners or psychopaths. Quite the contrary. They are disillusioned and disappointed with how things have turned out and how they are going. It's Bob Dylan singing that he used to care but things have changed. I really hope Socrates and Jesus are right when they claim that evil stems from ignorance and that we simply don't know what we're doing.