Airbnb is expanding beyond, well, Airbnbs. A broader business, however, doesn't make its stock a buy.

The company has become successful enough that its name has become a byword for short-term rentals of houses and apartments. "Should I stay in a hotel or an Airbnb?" you might ask when planning a trip to Florence.

In that particular case, you might opt for a hotel, given that Florence has recently expanded its restrictions on short-term tourist rentals. New York began sharply restricting Airbnbs in 2023, Barcelona will ban them entirely by 2028, Japan is cracking down, and the list goes on.

Amid that regulatory pushback, Airbnb has been looking for new areas of growth. It is rapidly adding hotels to its platform, a strategy some analysts cheer. "Investors continue to under-appreciate the acceleration likely from hotel and the broader cultural shift underway at Airbnb," Mizuho Securities analyst Lloyd Walmsley writes.

But Airbnb isn't stopping there. The company has already launched an Experiences business (go fishing in Central Park for $95!), and is looking to expand into car and equipment rentals, one-day gym passes, and much, much more.

"I imagine one day we'll have dozens, possibly even hundreds, of categories," CEO and co-founder Brian Chesky told CNBC in May, adding that Airbnb is looking to build "an Amazon for services, at least for traveling and living."

Investors seem optimistic about the idea. Airbnb's stock is trading at 27.1 times forward earnings, per FactSet, well above the 17.5 times for Booking Holdings and 14 times for Expedia Group. "To own Airbnb, you need to believe it can grow beyond core home-sharing into a broader services marketplace while keeping regulators, communities, and hosts onside," writes Sasha Jovanovic of Simply Wall St.

The growth in its core home-sharing business shouldn't be a problem. The company is set to report earnings this coming Thursday, and they could be impressive thanks to a significant tailwind from bookings around the World Cup. That's a one-time event, however; Chesky is betting the future on new businesses. "The reason our stock has been flat is that we only do one thing," he told Patrick O'Shaughnessy on the Invest Like the Best podcast. "We kind of started to saturate a little bit of the core idea, and we've started to reinvent ourselves."

Chesky is a brilliant communicator, but business reinventions are costly and prone to failure. It's time for investors to check out.