Since Bitcoin is a decentralized currency, it can be used for a wide variety of purposes, both legal and illegal. While there are many legitimate uses for Bitcoin, such as paying for goods and services online, there are also a number of illegal uses, such as buying and selling drugs on the black market.
The anonymity that Bitcoin provides makes it the perfect currency for black market transactions, as it is very difficult to trace who is sending and receiving the funds. This has led to a booming black market for Bitcoin, with many different websites and forums springing up where people can buy and sell illegal goods and services.
While the black market use of Bitcoin is a small part of its overall use, it is still a significant amount. This is because the total value of all Bitcoin transactions is around $1 billion per day, with a large portion of that being used for illegal purposes.
So, while Bitcoin is not solely a black market currency, it is still widely used for illegal activity due to its anonymity and ease of use.