On Monday, people were okay with playing the game. On Tuesday, people assumed you were making a rhetorical point and refused to play the game. Are you trying to say that CFAR lessons are a waste of money?! :D

More seriously: the difference could be in the people involved, but also in what happened before the game (either immediately, or during your previous interaction with the people). For example if you had some disagreement in the past, they could (reasonably) expect that your game is just another soldier for the upcoming battle. But maybe some people are automatically in the battle mode all the time.