OP, you’re posting on Mn, which is inhabited by an unusually high proportion of timid, withdrawn, socially-awkward or actively misanthropic people who either can’t make or keep friends, or don’t want to, or believe that their misunderstanding of the term ‘introversion’ naturalises this. So you’re unlikely to get balanced replies.
I agree that some friendships are situational to a particular life stage, job or setting, and agree with a pp that this is fine — there’s nothing wrong with these passing relationships, and they can bring a lot of fun and good feeling which isn’t lessened by them not lasting an entire life.
But absolutely there are friendships that survive changes in geography, life stages, and circumstances. I’ve moved around the world a lot and am still close friends with people from my postgrad days or previous places we lived, or jobs from 20 years ago, whom I now only see if we get on a plane to see one another, but talk to often. DH is visiting one such couple from his own student days this weekend in France. I spent part of yesterday supporting a UK-based Israeli friend from an old job who is distraught about family who may have been kidnapped or killed. I haven’t seen her since I left the UK, but we’re very much still in touch. I’m going climbing next weekend with a friend who was our architect when we renovated our old house.
I think one of the differences is that moving so much means I look round for friends and put effort into making friends with people I like, and retaining the ones I want to keep in my life.
I don’t really use SM, other than Instagram as a sort of visual diary for art or strange things I’ve seen, so that’s not a factor.