All the evidence suggests that people like sports and will pay to watch them. eSports is no different in that regard. What is different is the demographic skewing younger, and therefore with less disposable income.
I disagree that eSports are no different in that regard.
First, it's insane (to me) how many people watch American football and spend a lot of money doing so. The NFL and major league baseball (with the NBA distant behind them) make more money than most of the soccer leagues around the world combined. I cannot fathom the amount of money flowing through the NFL.
While football tactics, rules, strategies, etc., have changed, the game is understandable for anyone who has watched football since about 1920 or so. If you grew up watching football 50+ years ago, you can still comfortably watch today. Ditto for baseball, basketball, soccer, rugby, cricket, hockey, and so forth.
A quick google claims that GTAV, League of Legends, and Fortnite at the top games so far in January. I've never played any of those. I wouldn't know what is going on if I were to try to watch them. (Just Chatting crushes all games)
In 2012, the most popular games were Starcraft 2, World of Warcraft, Dota2, and League of Legends.
2017 I see League of Legends, PUBG, Dota2, Hearthstone, and CS:Go.
So League of LEgends seems remarkably constant, but the others are all over the place.
If you take a few years off gaming, you're lost in the streaming world--at least among the popularly streamed games.
While many Americans played football in school, almost no adults play football. I would guess that the majority of NFL watchers have never played football, but that's a pure guess. I would argue that it's very difficult to watch most video game streams if you aren't very familiar with the game. And since streaming trends move so quickly, it is truly a genre dominated by young males.
Who knows if the situation will always remain the same, but streaming is pretty solidly dominated by video games and thirst streamers, and both audiences skew male and young.