Because it's a boring, safe, traditional business model.

Instead they've bet on harvesting and exploiting information about the behaviour of the many, to ultimately allow them to exert some 'control/influence' over individuals.

And they're winning the business lottery with it.

More shame us for only considering ourselves when deciding whether or not to use a service like google. I can choose not to use google/facebook, but if everyone else uses them, they'll still have incredible power over me through the insights they gleaned about everyone else