When the Overwatch League debuted its first season this month, eSports fans came in droves, bought lots of merchandise and otherwise behaved like those who attend professional football, basketball and baseball games. Numerous traditional sports team owners have already invested in eSports, so when the Overwatch League was being formed, many investors were eager to pay $20 million for a franchise. Even Facebook has joined in, saying it will be the exclusive destination for multiple leagues from eSports federation ESL.

The Washington Post reports that, according to market research firm Newzoo, “annual revenue [for eSports] has grown more than 40 percent over the past two years and is quickly approaching $1 billion,” and “the total audience for eSports will approach 590 million worldwide by the year 2020.”

The International, “the major tournament for the game ‘Dota 2,’ featured a total prize pool of $24 million, with the tournament winners landing $10.8 million.” Among those who bought franchises for Overwatch were “New England Patriots owner Robert Kraft, Stan Kroenke (Los Angeles Rams), Jeff Wilpon (New York Mets), Andy Miller (Sacramento Kings) and Comcast Spectacor (Philadelphia Flyers).”

The Golden State Warriors and Cleveland Cavaliers are just two sports teams that have “sunk money into ‘League of Legends’ eSports franchises and other popular gaming titles,” and “Major League Soccer announced last week that it will launch an eSports league centered on the popular FIFA soccer video game.” The goal, says OWL’s Los Angeles Gladiators general manager/president Rob Moore, is to “reach people under 30,” and eSports is built for that demographic.

VentureBeat reports that, according to Blizzard, “the first week of Overwatch League drew more than 10 million viewers,” after showing 12 matches on Twitch in that time period. “At its peak, Overwatch League had more than 425,000 concurrent viewers.” In May 2016, Overwatch debuted “for PlayStation 4, Xbox One, and PC.”

Wired notes that, with the announcement that it will be an exclusive destination for several ESL leagues, “Facebook may have decided … it might just want to be a gaming platform.” ESL runs tournaments for “Dota 2,” “Counter-Strike: Global Offensive” and its own “CS:GO Pro League,” all of which will be broadcast via Facebook Watch, along with “recaps, highlights and a week-in-review show.”

With Facebook as a partner, said World eSports Association commissioner Ken Hershman, his group has “the best of both worlds,” since Facebook is not just a streaming platform but “obviously a social and engagement platform.” The game highlights will “live in Facebook Watch and surface on users’ news feeds as well.”

ESL’s reach on Facebook grew from 750,000 viewers to more than 25 million last year. On tap for the future are ESL matches in VR using Facebook 360.