Not if this guy kept emptying it... because there'd be a lot less than 3000 plays moving forward. But this guy won't have access to your machine likely going forward... so instead you trained a mercenary to go attack other ops. Still, it was pretty cool of you to put out a prize machine on freeplay. Most people (myself included) are not that generous.
Also you're not factoring in that most operators have to give a cut to the location... so this kind of play would really actually put you in the negative. It would cost you money to put out the machine and you'd have to be paying people to play and take your prizes. You mentioned the 50 prize balls, but not the minor prizes. Which are cheap but still a factor.
All of this is known though... you shouldn't operate true skill games if you don't want someone using their great skills.
Probably because it needed to be to make any money, with the location's cut and what not. Product is getting more expensive and harder to get as well.