I use it to keep in touch with far away or unimportant people. Second degree aunts, ex schoolmates, etc. Without FB it's a nightmare keeping in touch the few times I want to (people change email addresses all the time). Also, many groups are useful
It doesn't make any sense to complain about Facebook's business model and also not want to sacrifice a worthless personal account noone cares about.
We choose what we use and they choose how they make money. You can expect them to be ethical but they have no responsibilities to meet your expectations, as they have never promised to be a platform that respects privacy.
I don't like the "always on" part of WhatsApp and the like. I like FB because I can go on when I fell like. Who are you to tell me what I should use?