That's not how it works. New ideas are scarce, in that they require effort (and ultimately energy) to create. There are not "an unlimited number left", someone

That's not how it works. New ideas are scarce, in that they require effort (and ultimately energy) to create. There are not "an unlimited number left", someone has to actually create them. However, ideas are not rivalrous. Once they are created, everyone in the world can benefit from them simultaneously at no additional cost. Therefore, the immediate opportunity cost of allowing people to own ideas is far greater than for physical property.