2. You believe most people can't be trusted.
I won't argue that healthy discernment is important, but most happy people are trusting of their fellow man. They believe in the good in people, versus assuming everyone is out to get them. Generally open and friendly towards people they meet, happy people foster a sense of community around themselves and meet new people with an open heart.
Unhappy people are distrustful of most people they meet and assume that strangers can't be trusted. Unfortunately this behavior slowly starts to close the door on any connection outside of an inner-circle and thwarts all chances of meeting new friends.