We have come to a point where people who entered the market in Nov/Dec 2017 are starting to lose faith. Some of them are selling and some are still in the game but thinking about doing the same. This is because the crypto craze has reached its peak in that period and people were throwing money at any coin that was showing even a small sign of potential gains.
All of this fear of BTC never reaching its all time high again is causing the price to drop and it will probably continue doing so until at least one crypto project finds mass adoption. Will it be Ethereum or Bitcoin or some other coin, we cant know. Ripple has the biggest chance right now since they are the only ones trying hard to sell their product to banks and money transfer agencies.
To keep this answer short, I think BTC will go a lot bigger than 20k but time is a big factor now. The media wont talk as much about BTC until it starts growing again but it cant grow without media coverage. Mass adoption will bring new investors in, this will alert the media and if crypto finds a place in our everyday lives you can expect BTC to go a lot over $20k. I personally believe that it can hit close to a million per coin but only if cryptocurrencies as a whole become adopted worldwide. If they fail at mass adoption we could see BTC going back to hundreds of dollars or even less.