When I was a kid.
Nobody wanted to play with me when I didn't bring out my toys, so they could. Then later in school, they've made friends of groups, but I was not included in any of those. I have tried, but without success. I was laughed at, cause of my behavior and appearance.
Later in high school I have made a friend, but it was just because we were both nerds and outsiders, but she was still more outgoing like I was.
I thought it was better in adulthood, till I have found out my colleagues speak about me behind my back, and not nice things.
After this revelation, I told myself, It's not my fault they don't like. And if you don't like, it's your problem, not mine. I will not change myself for someone.