The Golden Ratio
A Blockbuster video near my house had a giant gumball machine near the cash that had special gumball-sized plastic orbs that instead had a free movie/game rental. So for 25 cents, you had the chance to win a $4.99 rental.
Well this was around for my entire childhood till one day I walked past the machine and noticed it was almost empty, and it looked like the remaining ratio of gumballs to free-passes was like 3:1.
When they first filled the machine years ago, apparently the employees just tossed all the passes on top and barely mixed it up. I came back with a stack of quarters and for $10 I got like 17 free rentals and 23 gumballs. The rentals lasted a few months, the gumballs lasted a few days.
Story credit: Reddit / SovAtman