Viewers of Netflix’s latest and greatest hit know there is no such thing as easy money when the stakes are high, no matter how basic the game. Social-media investors are learning the same lesson. Shares of Snapchat owner Snap Inc. lost almost a quarter of their value Thursday evening after it reported results.

Making money in the stock had seemed like child’s play. If you bought Snap back in mid-March of last year, you had yourself a “nine bagger,” with shares up more than 890% in around 18 months. Over the last two years,...

Viewers of Netflix’s latest and greatest hit know there is no such thing as easy money when the stakes are high, no matter how basic the game. Social-media investors are learning the same lesson. Shares of Snapchat owner Snap Inc. lost almost a quarter of their value Thursday evening after it reported results.

Making money in the stock had seemed like child’s play. If you bought Snap back in mid-March of last year, you had yourself a “nine bagger,” with shares up more than 890% in around 18 months. Over the last two years, Snap has dominated even its high-performing social-media peers.

That made a dash of cold, hard reality even more painful. On Thursday, the company said it missed even the low end of its third-quarter revenue guidance, reporting growth of 57% in the period—below Wall Street’s estimate of about 62%. Worse, the company guided to fourth-quarter revenue growth of just 30% at the midpoint, nearly 20 percentage points below analysts’ forecast.

In a conference call for analysts on Thursday, Snap seemed to suggest that Apple’s recent iOS changes had the biggest negative impact on its advertising business in the third quarter, with that as well as soft advertising spending tied to supply-chain issues affecting the current quarter. While none of that should come as a surprise to investors, the depth of their impact seemed to do so.

Perhaps lost in the shuffle were the positives in Snap’s earnings release. The company said its daily active users grew 23% year on year on the quarter, topping analysts’ expectations. Advertisers want to be where users are, so that growth should pay off once macroeconomic issues resolve.

One of The Wall Street Journal’s recent investigations of Facebook highlighted how young users have been shrinking slice of the company’s legacy Blue app for a decade—the very demographic with which Snapchat is particularly strong. Meanwhile, Pinterest’s second-quarter report showed the image-sharing platform lost 24 million monthly active users on a sequential basis, casting doubt on that platform’s ability to meaningfully grow its own user base in the near term.

Despite Snap’s issues in the third quarter, management commentary on Thursday’s conference call suggested Facebook might fare just as poorly, or even worse. Snap said its business was hit particularly hard in the third quarter by Apple’s ad-tracking changes because direct response ads, meant to elicit immediate conversion, now comprise more than half of its mix.

Whereas Twitter’s and Pinterest’s platforms are heavy on brand advertising, Facebook said last quarter that direct response ads continue to be the bulk of its business and its primary growth driver. Most ominously for the sector, Snap said the long-term impact of Apple’s changes “may not be clear until at least several months or more after the ecosystem stabilizes.”

Whereas Facebook faces growing pressure from regulators, near-term technological and macro disruptions will eventually clear for Snap. At that point, the camera company will have teed itself up nicely for significant growth with relatively new products such as Snap Map and Spotlight. Snap has one of the more exciting 2022 setups, according to Jefferies analysts Brent Thill. In an earnings preview, he warned that investors are likely overlooking tailwinds of these new products in addition to Snap’s augmented-reality monetization, focusing instead on the evolving privacy landscape and supply-chain disruptions.

A rocky stretch for social-media investors could be an opportunity to shift bets to more likely winners in this game.

Write to Laura Forman at laura.forman@wsj.com