This stuff has real world as well as emotional value. Just because it's a video game doesn't mean it's less important to those participating in it.
I've never met the majority of my coworkers in person and we're no less productive than when I work with other coworkers in person. The CEO is entirely remote too.
Also, what is "real" and what is "imaginary"? Time is real regardless of if I spend it on something "real" like work or something "imaginary" like a game.
If I put in 30 hours helping my team on something that I don't actually find fun or interesting because I expect my team will later put in the time to help me with something I do find fun or interesting and my team lets me down I'm just as annoyed at the lost 30 hours if it is a game team as I am if it is a work team. Heck, at least with the work team I still get paid for those useless hours.
If you blow up at someone during a sports game, there will be real-world consequences for you, eventually you will not be able to play that game at all in your geographic area.
If you yell at people over a computer headset it doesn't matter what they think of you, you can simply move on to the next group of people. Very rarely (mostly at the very top levels) does reputation matter. And at the end of the day you can simply name change and escape your rep.
Interpersonally the stakes are orders of magnitude lower in video games than in RL.
The survival instinct is also a stake that living things create for themselves.