If you don't have to pay for a product, you are the product being sold.

I think this line needs to be entirely retired from serious discussion. It's a gross simplification that relies on emotional manipulation (you're slave!) and does nothing to actually inform anyone.

First off there's nothing preventing (most) companies you pay from tapping into the same revenue streams as companies you don't pay. Outside of technical protectiona you usually just have a EULA with unilateral change provisions with all the protections, or lack thereof, that entails.

Fact ia that there are different business methods that are used to monetize free services. Selling your time and attention to advertisers is quite different from selling your location history. And as repugnant as the later may be it is still not selling you, it is selling information about you.

So yeah, question free services but question paid services and be upfront about why you question them. If you don't know how they make money, say you don't know. If you do know, share the details.