You don't.
Read Carefully: [url]http://www.bungie.net/en/View/bungie/eula[/url]
You are LICENSING the rights to play Destiny.
Any content that may have been on the Disc at time of purchase is not yours it belongs to Bungie and Activision.
Therefore you were never cheated out of any content as it was not yours.
If this is unacceptable to you there was a 30 day refund policy granted to you in the terms & conditions that you probably didn't read. If it has been more than 30 days you have no one to blame but yourself.
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*epic facepalm* Every single game company is doing this, and they have been for a long time. Why? It's obvious, you buy a copy of the game to play it, therefore what you actually buy are the rights to play that game. Of course you do NOT own the game, nor any of the disc contents, all you own are the rights to play it...and it doesn't make a difference for a gamer...at all.