More Americans than ever are cutting the cord in favor of over-the-top (OTT) video-streaming platforms, according to eMarketer. The firm estimates that the number of cord-cutters in America will surge from 33 million this year to 55.1 million in 2022.

That's bad news for traditional cable and pay-TV companies, but it's great news for the five market leaders in OTT streaming: Alphabet's (NASDAQ:GOOG) (NASDAQ:GOOGL) YouTube, Netflix (NASDAQ:NFLX), Amazon's (NASDAQ:AMZN) Prime Video, Hulu, and AT&T's HBO Now.

The top five OTT services in the US, by provider.

Data source: eMarketer. Chart by author.

According to the most recent data available, YouTube is the country's top video-streaming platform, but Netflix -- which had nearly 56 million paid subscribers last quarter (with multiple viewers per account) -- still leads in paid subscribers. YouTube's paid version, YouTube Premium, only had 1.5 million subscribers by about mid-2016, The Verge reported, and the company hasn't provided any recent figures. Reuters calculated that about 26 million Amazon Prime accounts streamed videos in the U.S. as of early 2017. IHS estimates that 46.3 million North American Prime accounts could stream video by 2020. 

The growth of these platforms, all of which rely heavily on original content to lock in viewers, could make it tough for other OTT challengers to gain ground. But that probably won't stop traditional media companies, telecom companies, and other players from trying to crack the growing market with their own streaming services.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. Leo Sun owns shares of Amazon and T. The Motley Fool owns shares of and recommends Alphabet (A shares), Alphabet (C shares), Amazon, and Netflix. The Motley Fool has a disclosure policy.