Why do we fear missing out?
The most basic theory goes a bit like this: We are social animals. Social animals experience evolutionary pressure to conform to their peer group. Thus, when a new group behaviour emerges we experience FOMO because we are instinctively afraid of being left out of the group.
Of course, this line of reasoning leads to more questions.
Why do we want to fit in so desperately?
The short answer is because it’s good for reproductive selection. Social groups are essentially status power plays where the individual with more status is the one that hooks with the best, with the most, or both. Stretch this behaviour over eons and you get present-day human behaviour.
Why do we keep feeling pressured to conform to the group after we have reproduced? Again, because it helps maximise our reproductive chances — the more children you have, the better.
Why are reproduction levels generally trending downwards despite everyone (theoretically) optimizing for reproduction? Because selective pressures makes us compete for status within peer groups, but modern society has made reproduction an optionality, no longer a necessary requirement.
I’m also curious why some high status individuals have so few offspring but I have no good theory other than it’s anecdotal behaviour.
Why is FOMO only expressed with some groups?
When Bill Gates buys a 25 million dollar house I don’t feel anything, why is that? My sense is status power plays are only played with close peer groups, to the level where reproductive selection makes sense. Bill Gates isn’t a close peer to me, he is more of an abstraction, a god-like figure that might as well be from another species, and for whom my primate brain is not in close competition for the approval of the same peer group.
FOMO is the other side of the competition coin: No competition, no FOMO.