BIGGEST DROP without a clear reason for it --> MARKET MANIPULATION

[Bharathi13]

Due to rise of cryptomarket in 2017 a lot of new peoples entered cryptomarket because they felt there is a ray of hope for bright future if invested in cryptocurrency sometimes as the cryptomarket were showing potential of profit on investment in short time. Peoples used to invest in each and every ICOs because there were few legit ICOs earlier which used to give guaranteed profits on investments in pre sale, main sale later the number ICOs along with that number of scams increased which helped in market manipulation. Recently I read one article about lawsuit going on Roger ver & Bitmain CEO Jihan Wu for allegedly hijacking Bitcoincash Network which is the biggest example of manipulation & resulted in crash of cryptomarket drastically. 
https://cointelegraph.com/news/bitmain-roger-ver-kraken-sued-for-alleged-bitcoin-cash-hard-fork-manipulation

[ukloon]

The problem with decentralised markets is that it is open to all sorts of manipulation. There is no higher authority to complain to as it is all community driven. All we can see is that it has happened before, and it always bounces back bigger and better than before