This is a two part question, let’s start with the logical high school. I was in high school in the late 90s and early 2000s in a very suburban conservative community. During my entire 4 years in high school I only knew of 2 other gay guys, and I did not learn of these guys until my Junior and Senior years.
I remember distinctly when I learned there were other gay guys in the school that when I learned about them it was because people were making fun of them behind their backs. These same people would pretend to be great friends with them to their face, but as soon as they turned their back the snickering would start. I was never friends with either of these guys either, they were both very different than me. One was a troublemaker who hung with the bad gang of kids (2 of his friends are in jail for murder) and the other was smart, but he was a big pothead. I did not fall anywhere close to either of these categories.
I hung with the cross country guys. We were a big family and spent a lot of time together. During season we spent over 45 hours a week together and that number did not go down too much in the off season. A few of the more influential guys on the team were very homophobic. I talked to one years later who in college had a gay guy in his frat and at first he talked about how he went out of his way to avoid him. Eventually he came around and realized that the gay guy was not going to do anything to him, but it took him a while. I loved running and did not want to be shunned by the group of guys I spent all of my time with, so I avoided coming out.
In addition to the friends factor at school, I was afraid of what was going to happen at home. I felt there was a good chance that I would be cut off.
So I never came out in high school because of friends and parents. In college it was not so much friends I was concerned about as it was my parents. If it were not for my parents I would not have been able to afford college. I needed to ensure the money would keep flowing so I did not come out.
Some will say that I could have come out in college to everyone but my parents, and that is probably true. However, I had built myself such a comfort shell in the closet that I did not come out at college too. Yes, I did have some friends who were rather homophobic but they were not that great of friends. In general homophobia was not too big of a deal for me in college.
However, I was in an organization that had our club offices right next to the gay clubs and it was not uncommon for people to make fun of them in our office. I always wanted to yell at them when they did this, but never worked up the nerves.