Evidently they are still pulling enough users and click through rates to warrant their reputation in advertising. Whether or not some numbers are propped up by bots, who's to know.

Imagine billions of people depending on their platforms, and most of them will be accessing it through their official mobile apps which generally will be harder to block ads on, and most people will not seek out those methods. It's the reason they push their official app so much. For some it is a lower priority for them, and some may even enjoy targeted advertising.

There are platforms like YouTube where you can pay to opt out of seeing ads, which is also another revenue stream.