For Christians, it's a time to remember and celebrate the birth of their Savior. For others, it's a good time to get together with family. It's also good for the economy.
Xmas is a time of celebrating with friends and family. If I get a couple days off of work (or an extended shift off of work) to hang out with the people I like, hell yeah I'm gonna do it. It's what they did before Jesus, it's what they did during Jesus, it's what we do after Jesus.