Illegal activity was behind almost 90% of all Bitcoin transactions five years ago — now this figure shrunk to 10%, according to Lilita Infante at the U.S. Drug Enforcement Administration.
Speculative uses are now responsible for most transactions today. That doesn’t mean criminals stopped using Bitcoin, it's just that the proportions have effectively swapped. The total volume of criminal bitcoin transactions has still increased over the years as dark market activity has grown.
The figures Infante states indicate that most criminals are still using Bitcoin as a means of payment for more than just drug deals. Criminal networks are increasingly finding digital currencies useful for other purposes. These include cross-border payments and money laundering.