AAA developers aren't trying to make games that earn $50K/day (while a game is getting 1MM+ installs per day). AAA developers can spend $100MM+ in development costs and are looking for titles that can make $200K/day or launch and make $75MM on day 1.

Indie developers would love to make this type of game, but the fact is that even with the monumental success the game has had from a download perspective (50MM downloads), it's still only making $50K/day. That's like winning the lottery. Most indie devs are going to make games that get downloaded fewer than 1 million times, which, for a title like this, isn't going to make more than 1-2 employee salaries (let alone the up-front cost of building the game for the first X months for free).