> Humans weren't built to live in massive societies with 100s of millions of people.
Humans were built to socialize and live in societies though. It's part of our own nature to group up and form communities.
Even for the social butterfly, the number of others someone can actually communicate with is capped at a reasonably low number.
Yes, but the size of community matters. In a 100 people tribe everybody knows everyone else. In 1M city most people are strangers, a.k.a. competitors, enemies even.
With the difference that the larger the cities, the less we know the people around us and socialize with them. Totally different if you live in a tribe of 200 people or a mega city with 20 million people around you.