Bitcoin can reach 20000$ by the end of 2018

I believe it can be!
yes i do believe that it can actually happen and that is the reason why i am still holding my coins today and not selling it because investors will soon hoard a huge amount of coins and the price will pump up again.
You should be holding your bitcoin because it is the best coin we have and the potential profits in the long term are great, if you are holding with the hope you will get those kind of benefits for the short term then you are going to be disappointed and what are you going to do when that happens? The most likely thing is that you will panic and sell for a loss.