Sorry kiddo, your parents are lazy and they'll convince you (and themselves) that they are telling you to help you grow. It's either that or you're Jewish and your parents don't want you to feel bad when 98% of your classmates, school decorations, school holiday songs, teachers, and commercials are focused on Christmas.
Chances are you're the youngest child and your parents are just done putting on this charade for so many years, it's no longer cute and your older siblings even seem annoyed. Your parent will strongly hint on Christmas morning how that ski jacket your sister got is just like that one you all saw together in the store, right?
One day, most likely when they are with their friends, they'll just will bluntly say "come on, admit it, you know there is no Santa right?" Your mind will go through a panic, wondering if you should say "yes" to seem cool, or say "no" for fear of getting in trouble somehow. But from that moment forward you can't seem to convince yourself they were just messing around and face reality.
How does this kid know there is no Santa? Who fuckin' knows? Maybe he has cool parents or something. But this kid will most certianly embarrass you in front of your classmates for not knowing. He'll will somehow know everything cool before you do. A few years down the road he'll mercilessly make fun of you when you don't know what "horny" means or what a blowjob is. Don't worry, everything will catch up to this kid later on, and he'll spend his forties living with his parents and working the same job from high school, very horny and not getting any blowjobs.
As you open that year's hottest toy "from Santa" your uncle yells to your dad, "Where did you find that Joe?! I looked everywhere!" Everyone goes silent, freezes and looks to you. He scoffs at everyone's nervousness, "come on, he knows... he's like 13." You're only 9 and no longer wearing the wool over your eyes.
These guys aren't method actors, and when you think about it, they must be partially insane to sign up to wear this heat trap of a costume and have whiny loud kids sit on their lap all day and demand shit. Maybe his beard comes down at the wrong time or you hear him swear, but it is the final straw to break your belief in Santa.
Sorry, I never thought this article would be how you found out. But you have to grow up sometime. At least that's what my uncle said.