Two arguments can be made. On the one hand, there are definitely more private places to be rented out then there are hotel rooms in those 5 chains. On the other hand, I'm not entirely sure that Airbnb can ever be profitable enough with all of those rentable places to justify the cost, especially since much of their stock is misused long term rental capacity that many municipalities are cracking down on now.
So yes, it is rather unlikely that Airbnb will grow enough to justify the market cap. This is tech bubble hype at it's epitome.
The best part about all of this, is that a company called PetCo recently IPO'd as well. https://www.forbes.com/sites/joanverdon/2020/12/04/pets-are-...
So ya, we're probably going to get hurt real bad at some point.