There’s nothing in your profile that would indicate what your situation is, if you’re caring for him at your home or his, is he in a facility, how old he is... And, it sounds like you are just plain angry.
I’m not sure how any doctor could confuse dementia and sleep apnea.
As the others have said, if Dad is not sliding down the dementia slope and is in control of himself, there isn’t much you can do. You can’t force him to do anything because ultimately it’s him who will suffer from not taking care of himself. If you are burned out and at your wit’s end, start making alternate plans for yourself or for him.
It’s my Dad. He was originally diagnosed with Alzheimer’s, that changed to sleep apnea. He passed the tests with flying colors. Since he stopped using the machine, he’s acting “demented” like before he was diagnosed.
Short answer is you can't. You can't make another adult behave in a way you would prefer. Even if this person has lost the ability to make good decisions for themselves, it's still very, very hard to make them behave in a way they don't want to behave. The advice most often heard on this forum is to wait for the crisis that forces a change in behavior
I’m not sure how any doctor could confuse dementia and sleep apnea.
As the others have said, if Dad is not sliding down the dementia slope and is in control of himself, there isn’t much you can do. You can’t force him to do anything because ultimately it’s him who will suffer from not taking care of himself. If you are burned out and at your wit’s end, start making alternate plans for yourself or for him.