Other than REITs and manufacturers/Industrials/transports I’ll bet that most companies aren’t highly valued by their real assets after adjusting for their cash and marketable securities... maybe throw in inventory in some scenarios as well. I take it that by real assets you are excluding intangibles. IP is extremely valuable in tech. Microsoft, Google, and Amazon come to mind. They are some of the most valuable companies on the planet. Much, if not most, of Disney’s value is in its content library. Same for other media companies. Broadcast TV and radio groups most valuable assets are their FCC licenses. Netflix, cable providers, wireless providers are all richly valued by their subscriber counts. The Big Pharma industry probably has more $100 billion market caps than any publicly traded companies and drug patents are their most valuable assets. Coke’s most valuable asset is its brand.
Saying all that. AirBnB does seem to have been bid up to at least 4x a reasonable valuation. It’s a system, a customer base, an inventory of rooms (that they do not have to spend money on to maintain), an overwhelming market share with a huge barrier to entry, it’s projected revenue and the revenue growth.