They are struggling. They IPO not due to the health of their business, but because so many dupes are putting their dumb money on the table these days.
A 5% monopoly tax on most rentals/hotels does give you a huge profit eventually.
Is there any paid service with actual monopoly yet? Amazon has market share, but also competitive prices. To me all of these big markets like taxi, food delivery and online booking seem rather low barrier of entry. And that the customers will be price aware. That can't be really compared with free services like Google, Wikipedia or Youtube...
Which ones will work and which ones won't is hard to tell, but that is indeed what investors are betting on.
At least Airbnb has a business model that could theoretically make it to profitability. An alarming number of these don't have any coherent path.