Theft, as defined in law:
"To dishonestly appropriate with the intention to permanently deprive"
Thus blowing your whole argument out of the water.
To steal something from someone, you permanently deprive them of that which you stole. Since they are still in possesion of it, you cannot logically have comitted theft.
Copyright infringement and theft are 2 different things.
Movie and recording studios are the ones that want you to think that they are the same.
If you think they are logically the same thing, then picture this.
What would someone rather you do to back up your CD?
1. Steal another copy from the shop
2. Make a spare copy of your CD and play that, keeping the original in good condition
Or, another comparison:
1. A person sneaks into and out of a warehouse owned by Sony and takes a copy of some album.
2. A person copies said album from a friend.
They ARE 2 different crimes with a different type of criminal and a different effect on the victim and the law recognises it as such.