The interesting part (and perhaps the flaw of the game?) was that once it looked like Mike controlled the big prize, then (as Tom pointed out) they switched from taking on each other, to taking on the house.  It was actually what they needed (a clear briefcase winner) to maximize results.  Even if Mike had not promised to split the briefcase, or if he ultimately kept it all for himself, they all still came out for the best because of it.  So the temptation of a big payday prevents you from accomplishing other significant profitable actions.  I suspect there is a life lesson in there somewhere.