I don't think it was overreacting, really. I'd be mightily pissed, especially if nobody owned up to it. They all had to know who it was using that stool.
If you all came home and your kid and his friends were sitting on the hood of your car, and when they got up it was all scratched and dented, would you all be as forgiving?
These are objects, but people should respect other people's property. Simple as that.
The hood of the car example does not fit because a hood is not something that should be sat on, like a stool in an aracde. And, a hood is not to be used like that and you dont have permission to sit on the hood, such as an $600 aracade game to be played with and these kids had permission to do so.
If this were a toddler, would you have beat the kid instead because they cannot pay for the damage?
Knowingly sitting on someones hood is disrespect for sure.
The cluprit here knowingly did not do this on purpose. Playing an arcade game and spinning a stool while watching or playing and concentrating in the heat of game play, is an accident.
And yes, shit does happen. Otherwise it would not have. Of course these stools are not supposed to be in the gameromm, I'm sure there are also many, many, other rules for your games too.
Sure, someone DID cause it, they did not knowingly and purposely says, hey lets swing the stool around and ding up this guys game. Sounds cool! You do it, no you do it!
Collect the money from your son to fix the damn machine and move on.
Or leave it unfixed for all to see making an example out of it, this is what happens when you don't pay attention and you will pay for damages.
Things will happen again for sure when a game is played.