It would be a terrible thing if the Bitcoin pattern is the same as in 2013-2015, it could be the end of 2018 is only about 4000 $ -6000 $, as I think if it might happen?
Let's look at the pattern in 2013-2015 below:

and this is the pattern from 2016 to the present:

What if it really happened, give your opinion?

Everything can happen, because this has become the true nature of the market, especially for markets that are more decentralized, meaning that their price fluctuations are vulnerable / easily manipulated by those who have a lot of money. So that we can reach the next step then we should use the HODL strategy only, maybe this method is more effective.