I take the opposite point of view.
I've only had one cavity filled and it was the worse mistake I ever made.
Within 10 years the whole tooth broke apart. But instead of going back to a dentist, I just let it naturally work it's way out and heal itself. If I'd got it fixed, it would have cost $3000

While I was at that first and only dentist 25 years ago, he told me I had several other cavities that needed filling, but I declined.
All those teeth are still doing fine and even the one that broke out has healed itself. The only thing that ever went wrong with my teeth was making the mistake of getting one filled. Now that whole tooth is missing thanks to the dentist. The rest of my teeth are perfect.

My theory is that dentists are out to make money. They fake things like kids needing braces and filling teeth that don't really need it and then do a piss poor job so you end up going back to them years later.
The 6 month dental checkups are designed as a sales opportunity to scare you into getting work done that isn't necessary.