Property laws exist to stop the strong from just taking what they want from the weak. Effectively, someone can point to something and say "this is mine, you cannot have it", and either society backs them up on this or it does not. The only thing preventing someone from stealing your car, house, money, etc are laws.

The same is true of digital goods. Someone can point at them and say "this is mine" and the either society backs them up or it doesn't. You can argue that you're not depriving the creator of anything by taking a copy of a digital good, but you are; you're taking away from their ability to support themselves.