Lying about your age for a cheaper ticket means you just sold the truth for five bucks.

Honesty rarely gets sold in large amounts. It goes in tiny transactions where the payoff is so small that the trade feels like nothing, which is exactly what makes the price worth noticing. The money is not really the point. The point is that you found out you have a number, and once a thing has a number, later offers only have to be bigger.

Next time an easy shortcut appears, set the actual gain beside what it costs to take it. Paying full price for something small is a cheap way to keep your line where you want it. No announcement required.