I know this is a way off-season question, but really: Do you believe in Santa Claus? Not St. Nicholas, who lived about 15 centuries ago. The other one. The grandpa with the white long beard, the red suit and cap, the black heavy boots, and thick eyeglasses. The grandpa we teach our kids to write letters to, so they can get their Christmas presents. That guy. Do you believe he exists? Do you believe he rides his sleigh every Christmas night and delivers all those gifts?
Of course you don't believe he exists.
You know he is simply an invention of some marketing people. You know the whole story is a fairy tale. And yet, you don't tell that story to your kids as a fairy tale, like you do with all other fairy tales. You try to make your kids believe this grandpa is real. And he really delivers their Christmas presents. You even bought that suit, put it on, and left the toys (or gadgets, or whatever) you bought yourself, under the Christmas tree. Why do you do that? So you deceive them that Santa Claus really exists. And seeing is believing, right?
You mean no harm though. It's your kids, after all. You want them to be happy. And there is the side benefit of the motivation for the kids to behave, so Santa will bring them a nice little - or not so little - present, next Christmas. Not a piece of coal. But although you mean no harm, your kids will find out - most often the hard way - that Santa Claus does not exist, and all what they have been seeing all those Christmas Eves it was you behind the Santa fraud.
And then what do you do? You lie to them, again!
You tell them that Santa is real, and they will see him again next Christmas. And they believe you, because they trust you. Daddy and mommy wouldn't lie to them, right? But you do lie to them. Although you know they don't trust you as much as last year. You try your best. And you get a bigger Christmas present, and a more convincing suit. You may even get a longer beard.
But it's too late. Other kids have discovered the truth, and spread the news like wildfire: their daddy and mommy (that's you) are liars. They are fraudsters. They mock their own kids, in hopes they won't find out what the truth is. And what hurts the most, is not the fairy tale you fed them. What hurts them the most, is that they believe you think your kids are stupid - and maybe you really think they are.
The Christmas Day your kids did/will discover beyond any doubt, that Santa Claus doesn't really exist, was/will be the worst of your life, and your short-lived career as a Santa Claus was/will be ended.
But after a few decades, your kids will do to their own kids, exactly what you did to them. They will know Santa doesn't exist - just like you did. But the feeling for the few years they believed in the fairy tale, was great. Why would they take it from their little ones? It's kids anyway.
Eh, kiddo?