Everyone knows everyone
Social capital is the concept I think is knowing and constantly communicating with really interesting people; this naturally means everyone knows everyone. Since people who talk to and attract interesting people keep on knowing more people just like them who have social capital.
Twitter makes this clear with the “Followed by” feature. The Clubhouse map rashiq made, made this clear too: all these rich/tech people know each other because its mutually beneficial to know them link to clubhouse graph.
Anecdotally:
There’s this person I talked to who said he was talking to another dude which my work friend said he talked to all the time. This person I talked to knew a teenager friend I have who pointed me towards this dude which my work friend talked to daily and consequently worked with them for sometime.
More often than not: the best people you can talk to via cold outreach who know many of the people you do.