Ranked List: Why does the market crash so hard ( January 2018 )

January 2018 has been regarded as the worst monthly decline ever since January 2015. The value of Bitcoin for example took a dive from almost $20,000 last year to around $8700 at this time of writing. Various alt coins seem to suffer greater setback as a result. What do you think is the most major driving factor behind all this? ( Suggestions are welcome in the comment section should we missed anything )