And what do they do with the 'pies' they collect?
They lend some of them out to people, but only on the promise of getting even more pies back. And sometimes their children are really bad at pie collecting and so the pies get returned when the pie collector dies.
Marketing only increases the amount of pie you get when compared to no marketing at all, it doesn't increase the amount of pie available to get however. The problem is not in grabbing more pie than everyone else, the problem is a shortage of pie being made available because certain people collect pies as a hobby and they are doing rather well these days and have fantastic new methods to collect and store pies, so leaving less pie around for everybody else.