It is normal that bitcoin is using in many crimes because bitcoin is a money. I know that we all are aware that money is the root of evil! It is one of the disadvantage of bitcoin because it can use in different crimes.
Bitcoin has so many great features to help illegal activities and crime occur easily and more convenient, that makes the criminals prefer to use bitcoin more than ever, everyone wants to be rich, no one wants to be poor and want to get rich quickly can only do illegal things. We can not say this is the disadvantage of Bitcoin because without these features, we would not be able to make a lot of money from bitcoin, if not used easily for crime, bitcoin will not be supported and pump the price as strong as it is now