I just read this article by Sam Harris about lying to kids and this section stood out to me.

I don’t remember whether I ever believed in Santa, but I was never tempted to tell my daughter that he was real. Christmas must be marginally more exciting for children who are duped about Santa—but something similar could be said of many phenomena about which no one is tempted to lie. Why not insist that dragons, mermaids, fairies, and Superman actually exist? Why not present the work of Tolkien and Rowling as history?

I've asked a similar question of myself many times. If my world is more fun, more exciting, more mysterious if I accept certain fictions as reality, why shouldn't I believe in all sorts of fantastic things? Why shouldn't I believe that pixies will sour my milk? Other people know the truth of these things, but is my life so much worse if I believe?

The reality we all experience day to day begins its construction when we're children. I definitely believe that fairy tales, and fiction in general have an immeasurable value, but only if they are acknowledged as fiction. The Santa debate, which Harris addresses directly, is a hard thing for me to wrap my head around. Were I to have children, I would want them to experience the few years of gentle naivete of believing in Santa, but I also wouldn't want them to ever believe that I would lie to them about what is ACTUALLY HAPPENING IN THE WORLD. I wouldn't be surprised if I were to learn that being lied to about Santa had some correlation to a child later becoming an atheist (If raised in a religious household). If my parents can lie about Santa, what makes any other thing for which they have no proof valid?