Because:

Hosting a pop-up is too expensive
Having to set up all the infrastructure for a pop-up from scratch: venue, kitchen, dining room, promotion, tickets, staffing, etc. is incredibly time/resource intensive. This limits who gets to cook/host.

Attending a pop-up is too expensive
The high setup costs drive up the ticket price; this limits who gets to attend.

Pop up culture lacks diversity
As a result, there ends up being a strong bias toward the same kind of people (e.g. privileged white guys) doing the majority of the cooking/eating and defining the aesthetic/ethos of pop-up culture. Read more