Why is bitcoin falling? the long-term bitcoin holders would be selling their bitcoin for fear of an attack with quantum computing that could happen within a few years, for this reason they would be anticipating to get their profits before it keeps falling further? .. the fact is that bitcoin will not return to the price levels of December 2017
As far as I know, there are several reasons why bitcoin prices are down :
Many countries either threaten to ban or issue regulations on cryptocurrency (such as China, Korea, USA, India).
New amendments to the US Tax Code - see cryptocurrency as property and many types of transactions will be taxed.
Visa and Mastercard networks stop all debit cards for cryptocurrency.
Many countries have increased ICO-related regulations (such as the United States, China, South Korea).
Many countries have increased the rules and regulations on KYC standards for trading floors in their territory.