I don't understand how anyone can not believe in Santa. Who do you think all the presents come from?
Seriously though, if people believe in the whole reason we have Christmas (God, Jesus, etc) then why is it any more far-fetched to believe in Santa?
Also, despite this Christmas being very lonely and stressful for me, I still believe there is a certain magic about Christmas. The belief in Santa, small children opening their presents and feeling so excited and happy, carol singing under lighted Christmas trees - It's a magical time of year. Just the fact that so many children believe in Santa, goes a long way to making it real. The person himself may not exist, but the spirit of the belief exists in the hearts of many, making it almost real.