It has little to do with Vanna wanting or not wanting to stop. The show desperately wants to keep her. As a minor fan of the show - with Pat Sajak gone, she IS the show. What’s his name that took over for Pat won’t be around long. He’ll do 3 - 5 years, get bored, and do something else.
Vanna is entirely unnecessary to the show itself today. International versions of the show don’t (for the most part) have a Vanna equivalent. Some person running the equipment off stage reveals the letters. Some versions have a good looking female model running the show, or pair her with a guy for some on-screen “steamy” interactions.
Vanna stays because the show needs Vanna to keep the audience. While it has some broad appeal, the primary TV demographic is people 65 and older. For them, Vanna is somewhat of an idol, or an aspirational goal. She is roughly their age at 68 years old, and looks (and IS!) fit and active. That is what they want to be, or what they remember being earlier in their life.
It also helps that those viewers have seen her in that role for the bulk of their adult lives. When she leaves the show, they will consider leaving as well.
She makes whatever it is that she makes not because of her skills at touching letters or walking across a stage, but because she brings viewers to the show. If she didn’t bring viewers, she’d be gone in a heartbeat. They pay her that much because that is what it takes to keep her coming back for more, and the show is still profitable after paying her that much.
–Peter
PS - I finally remembered ol’ what’s his name’s name. Ryan See-something or other. He probably polls well with the over 65 crowd AND isn’t offputting to younger viewers. Because face it. If your median age viewer is in their 60s, you constantly need to bring in younger viewers.