I've long entertained a dubious regard for the practice of lying to children about the existence of Santa Claus. Parents might claim that it serves to make children's lives more magical and exciting, but as a general rule, children are adequately equipped to create fantasies of their own without their parents' intervention. The two reasons I suspect rest at the bottom line are adherence to tradition, and finding it cute to see one's children believing ridiculous things.
Personally, I considered this to be a rather indecent way to treat one's own children, and have sometimes wondered whether a large proportion of conspiracy theorists owe their origins to the realization that practically all the adults in the country really are conspiring to deceive children for no tangible benefit. However, since I began frequenting this site, I've been exposed to the alternate viewpoint that this realization may be good for developing rationalists, because it provides children with the experience of discovering that they hold beliefs which are wrong and absurd, and that they must reject them.
So, how did the Santa deception affect you personally? How do you think your life might have been different without it? If your parents didn't do it to you, what are your impressions on the experience of not being lied to when most other children are?
Also, I promise to upvote anyone who links to an easy to register for community of conspiracy theorists where they would not be averse to being asked the same question.
I don't remember how old I was, but I remember coming up with a great argument as to why Santa couldn't exist and then telling my parents... who pointed out the huge flaw in my argument. I remember being disappointed, but deciding that I had to go back to not believing if my reasoning turned out to be bad.
Some time later, my friend mentioned casually that Santa didn't exist. It didn't surprise me at all and I just went with it because it seemed obviously right.
I didn't know what happened, but I mentally marked it as something weird that beliefs shouldn't do, so it stands out. Looking back, it seems more like a belief in belief, coupled with the fact that I didn't trust myself to change my beliefs without understanding why I was doing it.