For me the problem is multifaceted.

First there is the Tether problem, which demands further scrutiny but is enough to shake the market significantly.

Secondly, there is the issues of ponzis, namely Bitconnect, Davor and the 'lending platforms'. They have taken a large amount of 'mom and pop' money from the economy with their demise and a lot of other speculators pulled the plug also.

Thirdly, the transaction fees recently have been way too high to warrant practical use of the network for anyone holding less than .5 BTC.

The lack of regulation, and even the rumour of any kind of regulation is enough to shake the market for a day or a week. The volatility that makes the market so intriguing for speculators.

I see a lot of issues at the moment that have led to the price drop, but things are still up from this time last year - which is something people forget.