I was thinking of this story (just a poll I know):
Frankly I don’t trust FB self-reported numbers, but this is a personal opinion and not one I expect many to share. I agree Instagram and WhatsApp have helped keep users in the fold, those acquisitions were interesting too though - a very high price was paid for both (per user and for the companies), mostly in FB stock, which then arguably inflated the FB valuation, making the FB stock more valuable…
This is the least stable of the US tech giants IMO, but will be interesting to see how they evolve.