Three years after its botched IPO, Facebook is a Wall Street darling. (Blockbuster growth and profits for 12 consecutive quarters will do that for a company.) Investors traded shares of the company up 33% last year; the social media behemoth is now worth $293 billion. The message is clear: Wall Street adores Facebook.
The sentiment is evident on Facebook’s (fb) earnings calls. Analysts no longer use the opportunity to needle CEO Mark Zuckerberg about whether Facebook is still cool with teens or whether it can figure out how to sell ads on smartphones. (No need on the latter—mobile now makes up 81% of the company’s revenue.) Instead they lob softballs. How expensive can its advertisements get? How big of a Scrooge McDuck vault should we acquire for all that sweet video coin that Facebook is going to mint? On a scale of one to totally, how much is Facebook dominating mobile advertising?
Of 51 analysts following Facebook, all but four rate the stock a buy or strong buy. It’s to the point where, on Facebook’s recent fourth-quarter earnings call, the biggest risk factor CFO David Wehner could muster was that it might be tough to beat last year’s performance because it was so “remarkably strong.” Facebook usually plays classical music before its earnings call, but it may as well blast “All I Do Is Win” by DJ Khaled. In Khaled’s parlance, Zuckerberg knows all the major 🔑 🔑 🔑 .
It’s not unreasonable, then, to ask an uncomfortable question: Can Zuckerberg sustain his winning streak? With 1.6 billion people using Facebook each month, the company is running out of potential new users. Its lead in the mobile advertising market could shrink as Google (googl) and others quickly catch up. And Facebook’s next generation of growth engines—Instagram, Oculus VR, Facebook Messenger, and WhatsApp—are only beginning to figure out how they’ll make money. (The phrase “early days” is a favorite among execs.)
Generating revenue from Instagram will be a breeze—Facebook knows how to sell ads. Analysts estimate the photo-sharing app could earn $3 billion this year. But making money from other assets will be new territory for Zuckerberg and crew. WhatsApp, the messenger service it bought for $19 billion in 2014, and Messenger, its homegrown app, are expanding into the unsexy business of customer support, which is new territory for Facebook. Making and selling hardware, as it plans to do with virtual-reality headset maker Oculus VR, is even further afield.
If I sound like a naysayer (or in Silicon Valley speak, a “hater”), consider how people soured on another tech darling. For a decade, Apple (aapl) was imitated by competitors and idolized by market watchers. But throw in a disappointing Apple Watch launch and slowing growth in China, and suddenly good-as-gold Apple is a boring “value stock,” paying dividends and buying back shares. Even fanboys can be fickle, it turns out. And investors? Forget it.
A version of this article appears in the March 1, 2016 issue of Fortune with the headline “The Golden Touch.”