As we grown up, we can accept Santa isn't real, why not this?

WHY IS IT THAT EVERY NEW YEAR, WE HAVE THIS IRRATIONAL IDEA THAT THINGS ARE GOING TO FEEL RADICALLY DIFFERENT ONCE THAT CLOCK HITS MIDNIGHT; AND EVERY YEAR, WE IRRATIONALLY FEEL DISAPPOINTED WHEN EVERYTHING FEELS EXACTLY THE SAME AS IT DID JUST ONE MINUTE AGO; EVEN THOUGH, INTELLECTUALLY, WE KNEW FOR A FACT THAT NOTHING WAS GOING TO CHANGE