Bitcoin haters are claming that bitcoin is linked to criminality but this is not true for me. Criminality is linked with everything. Not only bitcoin, let's say.
I think everybody knows already that Bitcoin is a decentralized digital currency which means that there is no government involve in it. In addition of being decentralized, transactions made in the blockchain are also completely anonymous since you only have these cryptographic addresses in the whole process. So bitcoin is indeed a perfect tool for criminals to commit crimes because they can easily hide from authorities since their identities are concealed and the transactions are completely anonymous.