Normal time for it to drop after going from $14k-$17k region up to right under $20k. Exacerbated by the whole altcoin market making a strong surge and BCH being added to Coinbase and the accompanying propaganda in the media by Ver and BCH shills. BTC will probably stabilize here around $14k-$17k for a bit before resuming the upwards grind. Notice that the whole altcoin market including BCH has dropped along with BTC, so its just a general consolidation period now. The expansion re-engages in the new year.