From a formal logic standpoint, you're correct.

But the context of the parent's and grandparent's comments was (paraphrased) "if you don't pay, you're the product, therefore it makes sense to pay in this case". But given what we know of Meta and their ilk, we have good reason to believe this is absolutely NOT the case: you'll pay but you'll still be the product, and their offerings will keep on the road to enshitification. So parent comment is correct given this context.

I don't believe they were making the case that free Facebook is in any way healthy or good for you.