Who do really cares to check or verify on which their transactions came from if it is from a illegal activities or from the good ones? First of all, we are into a vast world of cryptocurrencies so basically we do not really know into who and which hands the cryptocurrencies we have got from numerous transactions really came from because it is quite impossible to track it down due to many numbers of transactions being processed day by day. Who do really know or even care to identify it first if the transaction they receive came from safe hands or not? Whatever or wherever the Bitcoin transactions we got came from will not be duly our responsibility anymore since usage and transactions of Bitcoin and being done continuously and simultaneously in circulation like paper money so it is just normal that there are cases money whether digital or cash will have a chance to came from illegal activities which we are already not aware because we do not even know that it happen.
The point is indeed there are many Bitcoin usages that can be related on illegal activities but why to worry about if you do not even have relation to those guys. It is just so happen that upon circulation of the cryptocurrency, a chance of obtaining transactions coming from illegal activities could be possible. But that was just because of the circulation process. Actually we do not care at all into who will be the transaction be sent out or who will be the next one to handle those after we have done transacting it.