I won't consider this a rally since we came from a huge dip and bitcoin hasn't recovered yet. This may be a sign that bitcoin is slowly recovering from its losses from the bloodbath due to the BCH drama.
People do have lots of money when it comes to the month of December, so it's one of the reasons why there's a spike on bitcoin's value. Some people are trying to purchase more bitcoin hoping that by next year they can profit from it. This trend is very unpredictable and might as well make you lose your investments so better invest only and amount that you can afford to lose and always set a goal of when to stop for greed will make you lose everything.