You may be right, but I have a feeling she's got more above the neckline than below it. (not that it would be hard with her frame)
Here's my reasoning:
1. She doesn't need to make money, but is doing that very successfully right now.
2. She could have stepped into her father's business and always been seen as the 'heiress' - she might yet choose to do that, but I doubt it.
3. She can cook. As silly as that sounds it's not something a pampered princess would have the discipline nor desire to learn. Sure it's not rocket science but it's something other than just 'see how I spend my money'.
4. Maintaining her figure is undoubtably costly, but that too requires some discipline when you are backed by nearly unlimited cash to eat what you want.
Those things lead me to believe that she's using what ever she can to gain her own wealth quickly. The video's the silly tv shows, the Carl's Jr. Ad, etc... it's all for the publicity and to separate herself from the 'Hilton heiress' title.
Of course, she might just be a stupid spoiled whore.
Or the unlimited cash necessary to put magical weight loss powder up your nose.