Superstition and tradition...irrational?

I wonder what is it about tradition that motivates people to follow it. It's Chinese New Year right now as I write this and there's all sorts of chinese beliefs and superstition such as not cleaning house during this season because one might sweep away one's luck, and one should cut his or her hair before the celebration (I forgot the reason for this) to the tradition of buying and wearing new clothes because it's supposed to be a 'new' year. You would think these are such antiquated practices but I was surprised to learn that a lot of people still practice it..maybe out of fear in case the superstitions turned out to be true? I guess in this day and age of science, people have not changed much in their thinking and dare I say..rationality?