I used to think like that - then I had kids....
I don't do tooth fairy or anything else but found that despite trying, I couldn't avoid the santa thing. I also didn't need to even say anything - society, school, friends, grannies - they do it for you.
Eldest son came to me one day and said 'it's you and dad isn't it' , I just asked him how and when did he know. He said it was kind of obvious for a while but that he enjoyed the illusion while it lasted.
It the idea of 'magic' that they like - not necessarily anything to do wth father christmas.