I have a slightly different perspective on this — I don’t know how common this is, but looking back on my feelings on Santa Claus as a young child, they had more to do with belief-in-belief than with an “actual” belief in an “actual” Santa. It was religious faith as I understand it; I wanted, vaguely, to be the sort of kid who believed in Santa Claus; I looked for evidence that Santa Claus was real, for theories of how he could be real even if magic wasn’t. So the lesson it taught me when I stopped believing in the whole thing was more of an insight about what it was like inside religious people’s heads.
I have a slightly different perspective on this — I don’t know how common this is, but looking back on my feelings on Santa Claus as a young child, they had more to do with belief-in-belief than with an “actual” belief in an “actual” Santa. It was religious faith as I understand it; I wanted, vaguely, to be the sort of kid who believed in Santa Claus; I looked for evidence that Santa Claus was real, for theories of how he could be real even if magic wasn’t. So the lesson it taught me when I stopped believing in the whole thing was more of an insight about what it was like inside religious people’s heads.