IHS’s forecasted growth of the competitive video-gaming industry. The company expects viewers to watch nearly 4 billion hours of “esports” this year. (IHS May 2014)

In my day, video games were not spectator sports, star players were not celebrities  and “professional gamer” was definitely not a legitimate career.

But in the intervening years between my day and the present, there’s apparently been a big shakeup in the world of “esports,” or online games: According to a report released yesterday by the market research firm IHS, people watched 2.4 billion hours of video games in 2013 — almost double the year before.

That’s not 2.4 billion hours playing video games, a self-evidently fun, recreational activity that many people have indulged in since the Atari days. It’s 2.4 billion hours watching other people play video games. In the words of the IHS report: “esports videos have rapidly transformed from a niche activity into a widely-watched, global, cross-platform entertainment category” — albeit one with an appeal that some will scratch their heads at.

A couple factors are at play in the rise of esports. First, online video streaming has become a powerful force since platforms like Twitch — now the Internet’s largest game-streaming platform — launched three years ago. At the same time, per IHS, publishers (and advertisers) have begun to pursue this kind of streaming more aggressively, putting the games in front of more viewers.

That’s helped Twitch amass audiences in the tens of millions — and it’s helped gamers like PewDiePie, the quirky Swedish “game commentator” and YouTube’s most-subscribed channel, to make a living off his work. (Slash play.) It’s a pretty good living, too: In March, The Atlantic estimated that Pew, real name Felix Kjellberg, makes  $140,000 to $1.4 million a month.

That certainly explains the explosion of competitive players, live-streaming their games away for fun, followers and profit. But it doesn’t answer the essential question: From a spectator’s perspective, where is the fun in watching someone else play a game you could so easily take part in yourself? It’s not like, say, Ping-Pong or synchronized swimming, which require a certain level of training and physical fitness. It would certainly seem to lack football or baseball’s mass tribe-forming, identity-conferring cultural appeal.

Esport adherents reject that kind of comparison — video games, after all, require their own kind of skill. And if you don’t believe that esports have become a mass phenomenon, you can consult one of the 32 million people who watched the final match of the League of Legends tournament last November. That is, per The Daily Dot, more people than watched the World Series final between the Red Sox and the Cardinals that same year.