In reading about sports like football or hockey, I find it sad when a player has to retire in their late 30's because their body is letting them down. I wouldn't have guessed that a professional Starcraft player would have to stop in his 20's.

From ESPN's article Starcraft - The beginning of the end for legend Jaedong:

But as transcendent as his play was, he could not elude the passage of time. Now, at 27, his body is no longer capable of sustaining the prolonged physical strain of top level StarCraft. It takes only a few games for his eyes to start drying out, his wrists and fingers to start throbbing in agony.

It reads like something you'd hear about a quarterback nearing the end of their career.

For Jaedong, training has become an act of conscious self-destruction. The best doctors in the country have urged him to quit. They told him that no procedure could undo the damage done to his wrists.

If the fact that ESPN has an Esports division is surprising to you, there's a whole world of professional video game players that's slipped past your radar. From Forbes.com:

Esports is a fast-growing industry. Most think the events garner a few thousand attendees. Most would not expect them to be more popular than the Superbowl but the finale of the 2017 World Championship (Intel® Extreme Masters) in Katowice, Poland just set a new record for live attendance - more than 173,000 attendees - that's about 100,000 more than the Superbowl last year.

and

The Intel Extreme Masters World Championship 2017 reached more than 46 million unique online viewers. To put that figure in context, per Nielsen, the Trump inauguration TV audience was 30.6 million.

I don't think esports is going to replace baseball on tv right away, but advertisers will follow the viewers and the money follows the advertisers.