When I was 4 or 5 I told my friend (same age) that there was no Santa. Boy, did his mom give my mom hell!
That’s a little like Isaac Asimov who as a precocious child did a mathematical calculation of the time required for visiting each home and told his little friends he didn’t believe in it. And he was also Jewish so didn’t celebrate Christmas anyway.
His young friend John Campbell who later edited Astounding always won hide and go seek by using US Navy search tactics of the area around him. Not any fun.