Criminals are increasingly using bitcoin for illegal transactions, preferring crypto-currencies, whose transactions are more difficult to track.
I have to disappoint you. Less and less Bitcoin transactions are used for illegal things. The number of serious transactions is increasing and the number of illegal ones is decreasing. You could read this in the news in the last weeks. Besides, it is not nice to use Bitcoin for illegal things, because he is only semi-annonymous. There are companies that have already analyzed the blockchain and know what Bitcoins are used for.
