They're just using their name like everyone else who has a "name."
Whether you're a media celebrity or a sports celebrity or a political celebrity, etc, - right now in our culture that's worth $$$$ - at least while you still have a name.
Just yesterday I heard a report of how much money even those celebs who have passed on are still earning for their estates. I think Michael Jackson was the most last year - added 75 million to his estate - but Elvis is still adding multi millions as are many others.
As for QVC, they get to choose who sells and I get to choose what I buy.
I'm fairly certain I'm not all that much of a celebrity buyer. I don't own any Tova or Louis or Isaac, I've never watched Kathryn Zeta Jones, and on and on. I just don't know the whole psychology of why TV has made them so valuable, but it has. My brain goes all the way back to Dinah Shore telling us to "See the USA in your Chevrolet" and all of a sudden I hearing that tune over and over. Kind of a neat memory although it's been decades since I owned a Chevy!