I’ve gotta believe (at least for my own sanity) that the vast majority of users aren’t paying any money to use the apps

The goal isn't to get a little buy in from lots of people so much as it is to a lot of buy in from a few people. That's the standard model for Free-2-Play-Pay-2-Win games.

Chasing the Whale: Examining the ethics of free-to-play games

My research didn't just focus on triple-A PC games either -- many of Nexon's free-to-play titles came up numerous times. One player told me that he has spent around $3,000 on MapleStory, including dropping a whole $500 in an attempt to create a single weapon in the game. But he says that he is easily one of the lower-end players, and that he regularly talks to people who have spent upwards of $10,000 on the game.

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Another player I talked to found themselves spending more than $5,000 on a Nexon game called Mabinogi, mainly on cosmetic items. "There were plenty of times when the rent would go unpaid because I had spent the money on the game instead," he says. "However, I don't know if I can blame the game for that. If I hadn't spent the money on Mabinogi, I would have spent it on something else."

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I also came across numerous far more outlandish stories. One player, who called himself Gladoscc, told me that he used to play a web-based MMO called eRepublik, in which players waged wars against each other. In total, Gladoscc spent more than $30,000 on the game. "The geniusly evil part about eRepublik is that you have to spend money in order to neutralize the enemy's money," he says. "It's spreadsheet PVP, though. The social aspect is what kept me in."