The opinion that it is real is also not a fact. We're not talking about physical things. They're made up rules about made up things. It can all be different if we agree to make it so.

IP isn't a concept that has existed in all cultures for all time. It's not inherent to group dynamics or humanity. It's not even a concept that's fully respected by cultures that claim to care about it.

Law is all about enforced opinion on what others should say and do.

Even property is a misnomer on that regard. The proper of someone is certainly more spontaneously matchable with one corpse. If anything, a land encompasses people, and someone psychological traits are indeed more property of the person but they can make it lasts through some expression of it only in external support which are distinct from their proper self.