It could be China, but I don't think so. We are getting stronger and stronger towards FUD. This is a normal and healthy correction. Have in mind that the price increased from 10k to 20k in several weeks. This is crazy, so the correction is.
No one can tell the exact reason why it is happen, but speaking of dropping, it's normal in the situation of many different token/coin existing now. I think that's the reason "WHY", due to it's different value also included.