Bait and switch. This is what big companies do. They buy products that are a threat to them, or allow them to address the threat of another company. Then they offer the bought company's services for free for a period. Then it ends.
The point is to kill competition so they can settle in and collect rent.
> Then they offer the bought company's services for free for a period. Then it ends.
It ends because there is an expectation of continuous growth. Eventually the predatory company starts corrupting the free model to increase revenue incrementally (all the while, internal development costs start to rise with bureaucracy) until the revenue growth is outstripped by development cost or market demand falls to equal/below a measurable amount.
Usually before, but at various times, some smaller startup with funding to stay alive or a novel business model grows with more agile process and lower cost expectations while the old predator tries to flail about (reducing ads or subscription costs) shedding users who invested, all the way down while maintaining all the bloat.
The point is to kill competition so they can settle in and collect rent.