Fantastic story, but there may be some selection bias at work here given that the pro ballers at the camp are by definition people who are choosing to continue playing baseball after retiring which may give you a higher likelihood of running into players who intrinsically love the game. The kind of player who gets a big contract and loses some motivation isn't likely to opt in to playing at a fantasy camp after retirement.[
I've had very limited personal exposure to pro athletes, but from what I've seen they are VERY competitive people. A couple of cases in point: I went to the Red Sox fantasy camp a few years ago, and former major leaguers served as managers and coaches for the camp teams. As you can probably imagine there was a wide range of talent and fitness levels amongst the campers. There were some relatively young guys who could still play well and there were some older guys who were just happy to DH and then just sit on the bench and catch some rays. In my first camp game my team had a 10-0 lead after 3 innings, but then we changed pitchers, and the other team began catching up, but we still had the lead going into the last inning. Our manager told one last guy he was pitching the last inning, and this guy immediately started talking mega trash, to the point where he was getting funny looks on our bench. Needless to say, this guy couldn't throw a strike or even get anyone out and we ended up losing. As soon as this guy got back to the dugout our manager pulled him aside and gave him a thorough ass chewing. Never mind that we actually paid to be there, he was really PISSED at the guy. A few days later we were on the other end of a rally. We were losing big but started to rally. One of the camp rules was very a liberal use of pinch runners. Anyone could be run for at any time, and you could run for the batter once contact was made. The umpire would draw a line in the stand and the runner would have to stand behind it and he could run to first once contact was made. Now this was toward the end of the week and lots of guys were coming up somewhat lame, and only the guys who were really in shape could still run fast. We had about four guys like that, and we were doing all the running, and we scored the winning run in the bottom of the last inning. In the clubhouse afterwards I went to see one of my teammates. The Pro's lockers were interspersed with ours, and the losing manager's locker from that game was close to my buddies. My buddy wasn't there, but the pro was. He was really PISSED too. He actually asked me "How many f*****n pinch runners do you guys have. You only had your fastest guys running those last few innings". Now mind you the camp itself was a glorified beer league, so I asked my manager, who was a really good guy, if the pro's had a bet or some kind of pool concerning the league. He told me no, that's just the way they are, very competitive by nature.
That said, my impression is that generally pro ballers are really competitive folks but I have no doubt there are occasional exceptions. There have been enough players over the years that sign huge contracts and then immediately fall off in production that I have to wonder if loss of motivation/distraction is a culprit in at least a few of the cases. I don't want to call out anybody in specific as I don't know any of these guys personally and thus have no basis to speculate on any individual case.