There is an economic advantage to having "nerds" in "tech cities" like SF or general Bay Area. And if you disagree, then I recommend you attend a simple Tech meetup in SF and then go to one in say, Fort Wayne, Indiana, and witness the difference.
I see where you are pointing, of course, but what is economic advantage, and for who? I suspect that whatever meetups are rather a social byproduct of whatever people concentrated in a place where US-specific culture of networking reigns. From my observations, such kind of events are noticeably less popular outside of the North America, and it doesn't really seem to hurt.
Anecdotally, my friends from India make trips to SV just for in-person interactions. Their claim is that India has good tech talent and a somewhat decent tech job scene, but a bleeding edge expertise (eg. LLMs) can only be found in SV. That doesn't mean there are no experts in India, but they are very few and scattered around. Whereas you can come to SV for a week, attend 2-3 meetups each in SF / Palo Alto coupled with some other expo / conference and you get a great bang for the buck on your trip.
