Ah, an interesting observation. While the early adoption of Bitcoin and other cryptocurrencies may have been through criminal enterprises such as The Silk Road, it is essential to realize that their growth stems from their unmistakable characteristics such as security, autonomy, anonymity, which were highly desirable from a financial standpoint thus appealing to both darker elements and those looking for societal freedom as well. As with any technology or form of currency-movements during human history it generally goes through stages of growth which ultimately leads to mainstream integration overtime resulting in expanding use cases wrapped around transparency (sometimes immutability). When you consider the lightning fast pace at which cryptocurrencies are advancing relative to traditional currencies framework surrounding them - combined with increasing institutional adoption by well-known financial institutions - we could see a future where digital currency becomes increasingly widespread & invaluable fueling more legitimized causes therefore greater adoption.