Whatever your particular mountain looks like, eventually the blur of your youth is behind you, the dust has settled, and there you are living your life—when one day, usually around your mid or late 20s, it hits you:
It’s not that easy to make friends anymore.
Sure, you’ll make new friends in the future—at work, through your spouse, through your kids—but you won’t get to that Tier 1 brothers level, or even to Tier 2, with very many of them, because people who meet as adults don’t tend to get through the 100+ long, lazy hangouts needed to reach a bond of that strength. As time goes on, you start to realize that the 20-year frenzy of not-especially-thought-through haphazard friend-making you just did was the critical process of you making most of your lifelong friends.
Well, shit. That means most of your lifelong friends are made, and that some of the people closest to you are somewhat arbitrary! And might even be people you don’t all the way like at this point anymore!