The massive bull run of 2017 gives some context for the slow bleed of BTCUSD in 2018.
While the failure of the parabolic advance in '13-'14 retraced more than 80%, the 2018 bear market has only retraced 61.8%, providing an argument for BTCUSD sinking further to $4000 as the bears continue to show dominance.
I am not an expert, and this is not investment advice.