3 reasons.
1. No one in my family celebrates it, the only thing we celebrate is the new year and give gifts at that time.
2. I'm atheist. Christmas was originally the birth of Christ, and I'm not one that celebrates that since I'm not a christian.
3. -blam!- the commericalism today. Same shit goes with Thanksgiving. It's all about companies trying to get you on deals so you could buy their shit, and when people really want their shit, they'll tear down and kill one another to get it. So materialism is a bitch.