Like any currency or technology, Cryptocurrency can be used for illicit transactions.
However, quantitative studies indicate that the extent at which virtual currencies have been used for illicit purposes is no greater than that for national currencies.
Covered in an article from Forbes studies show that only 0.34% of all cryptocurrency activity was of criminal share. On the other hand United Nations (UN) estimates that between 2% and 5% of global GDP is connected to money laundering or illicit activity. By those facts it is fair to conclude that cryptocurrencies are used way less in illicit activities compared to "regular money".
Furthermore, the anonymity aspect of Cryptocurrency has been greatly exaggerated by the media. While the Bitcoin system itself does not directly identify its users, every transaction that has ever occurred in Bitcoin is stored and logged forever in the publicly accessible Bitcoin blockchain. Whenever Bitcoins are used for purchasing goods or services, or exchanged to a national currency, the store or exchange provider can identify the customer and conduct compliance checks.