Unfortunately this happens all the time, if you pay attention. It happens so much that it gets tiring to confront all of them. However, it is not good for the pinball community to let bad conduct go unchecked. I think it is always a good idea to politely confront them, and if they get belligerent, aggressive, or hostile report them to Event Staff. If people want to elevate their rudeness to violence - go for it - get arrested and get piled on by the 96% good people in the hobby.
Oddly enough many of the rude self absorbed players that I noticed were wearing "Good for pinball. Bad for Networks" shirts. I though it very ironic that rude ignorant people that are in fact bad for pinball and the pinball community were wearing "good for pinball..." shirts.
One of the people I confronted tried lying about how all his friends walked away (another act of poor pinball etiquette, if it had been true), allegedly leaving him to play a 4 player game by himself. I knew that was a lie because I was watching him for a while, when I said that was BS, he switched to something like - too bad, I'm gonna keep doing it. I lost my cool a little and used some rude language. He shuffled off to take off his sweatshirt (revealing his "good for pinball..." shirt) and put ON a mask for a little while - presumably because he noticed me leave the pinball line to engage Event Staff and wanted to change his appearance.
If I ran a show I would log complaints, have event staff follow reported offenders and be proactive about bad behavior and most importantly I would eject people that repeat bad behavior, or threaten violence, and I would permanently ban people after 3 or 4 incidents, or a single incidence of threatened or actual violence. Of course permanent bans would require checking ID at badge pick-up/purchase. Utilizing the location's Trespass laws would help deal quickly and aggressively with problematic people if they return.
Now balancing that out is that sometimes extra games by people were not their fault on the Connected Sterns. I had it happen multiple times to me that when I walked up to a game with one or more friends and pressed the Start button for our number of players, it would Start more games than that because the prior players had Logged In the Connected thing and so the first Start press would add 2-4 players and any additional presses would add more players (capped at 4 of course). I never did track down Gomez to offer suggestions, but I suggest that the Stern Connected thing add a Convention setting that automatically logs players out after the game. Additionally, the game should forget any scanned in player that doesn't start a game within a few (1-3?) seconds. I saw people walking around to empty games and scan in on as many games as possible without playing so that when others walked up they would likely get credit for those plays - for whatever benefit or honors that might impart, if any.