The main purpose of a business is to generate profit, not just revenue.
Apple is pretty clear evidence that you don't need a massive market share to be highly profitable.
> be a hermit and stop using FB and WhatsApp
Is that seriously how you see this? How exactly do you think people lived 10+ years ago, before either of those things existed?
I haven't had a Facebook account for many years and I've never had a WhatsApp account. Does that make me a hermit? Should I inform my wife and son? Will my friends already be aware of my hermit status, or will you inform them for me, because obviously without Facebook or WhatsApp I have no possible way to communicate with them.