You can say "it's not a sport" all you want, but $4 - also known as eSports - is a thing, and, as this chart from $4 shows, it's only expected to get bigger.
In its $4, market researcher $4 thinks eSports at large will make $696 million in revenue in 2017, with its total audience - be it hardcore fans or those who just watch the bigger game championships - reaching 385 million. By 2020, Newzoo projects, those will reach $1.48 billion and 589 million, respectively. (That revenue figure doesn't include money made from eSports-related gambling, either.)
That'd still fall well behind major sports leagues like the NFL and NBA, and the relative inscrutability of, say, "$4" - the most popular competitive video game in the world - still makes it harder for newcomers to get into. Plus, while sports media titans like ESPN has $4 the trend, some of their forays into gaming $4.
But eSports' fans are overwhelmingly young and online, $4 $4 $4 $4 are increasingly dipping their toes in the sport, and more and more game developers are building their titles to have eSports-friendly features. Put it all together, and these sort of expectations may not be unreasonable.
Business Insider/Mike Nudelman/Statista