Every person is a threat. You just don't know what they might do. Keep them at distance. Don't be open with them. Avoid the phone like the plague. Just communicate through facebook and email. Find one single person you can actually open up to. Actually be real with. Only one! One person can supply your every emotional need, at least until you've reproduced.

At least for all others (at least) every face to face interaction, every speaking interaction, is an act. A somewhat stressful act, because it's somewhat dishonest isn't it? As it is an act. And because, again, every person is a threat.

And those who didn't play it like this died. Slowly but surely mankind reached this point. Being suspicious, being full of fear, assuming the worst, demonizing, these things work. The goal is not for the individual to have a good time. The goal is for the individual to reproduce and this is how it's done. One just barely has enough of a good time that they bother to stay alive and reproduce, mostly thanks to an awful memory.

The side effect is that this world is hell. Bearable to the extent you ignore or constantly forget virtually everything in it.

And that too by the way, has been a goal of evolution. The people who manage a twisted sort of intelligence, where they can operate heavy machinery, fill out difficult paperwork, determine exactly which act to put on, etc, at the same time that they're oblivious to just what this world is and what they're doing, these are the people who pass on their genes.