I guess it depends on your answer to the following questions.
Is Chess a sport? Go? Scrabble? Poker?
None of those require any physical skill but do require a substantial amount of mental and psychological skill to compete at top levels.
If you’re actually comparing time spent in the sport, then it’s a very interesting argument in favor of e-sports. US football is only about 10% actual sport, the rest is posturing, cheerleaders and commercials. I mean, you could watch an entire game in 15 minutes. Baseball isn’t much better. Soccer (or actual football) is at the top, naturally. Hockey – my favorite sport – isn’t too far behind.
E-sports are more akin to baseball, in that there isn’t a time for the game, so much an end goal. It could be edge of your seat for 30 straight minutes, or it could be junk for everything but a few rushes. The quality of the match depends largely on the ruleset, the game being played and the skill level of the players (both reflexes and the meta).
I’ve watched a couple SC2 matches and while there’s less action than a MOBA or FPS, the strategy application in that game is impressive. Macro and micro management is a very hard skill set to refine and does pay dividends after the competitive arena is closed.
While there’s certain financial benefits to pro sports as we normally see them, it’s hard to translate a good basketball skill set to another field. Leading a raid, playing ladder ranks or hitting the stage in a MOBA final seems to me, to have a larger real-world cross skill impact than a physical sport. Maybe that’s some compensation for the lack of money in field. For comparison, in my super lack of depth google search, Messi makes more than all e-sport purses in a year combined.
Still, e-sports are a rather young field and with more time and a larger pool of players, I think there’s a pretty interesting future in line. I’d certainly like to see more of the “thinking person’s” games available.