FRom how I see it and what ive read, its likely manny reasons behind this happening, and high transaction fees+ slow transactions is sertainly 1 of them, but ther eis also a large market maniopulation going on that took a new level when futures markets entered.
One thing that was not mentioned in this acticle though that is likely to be an effect aswell, is tha new US tax bill that may be implimented in early 2018 that is aimed at crypto cyrrency returns. Stating that a person ows tax on gains in relation to the first crypto that person ever got. (for what can be tracked that is) And that is then a reason to sell or move your cryptos before the end of the year.

Alwayas interesting to read others perspectives and yes, a recovery and posible new highs is likely to come. But i personally believe btc wil reach its max price ever in 2018 before some other take over as the largest.