So Unity is a digital ad company that gives away a game engine, or sells it at a loss, as a way to sell ads targeted based on what they know about the people playing the game. Ad revenue is in decline across the whole industry, so now Unity is looking to get a bigger slice of the pie by displacing AppLovin as the data harvester/ad provider

Aside: I wonder how much user data Unity-based games harvest from mobile devices. This may shed some much-needed light on privacy, advertising and mobile games.