People use dark web for conducting illegal business and buying illegal stuff, this simply states that Bitcoin can be used for illegal activities.
The main reason bitcoin is falling out of favor on the dark web has to do with the sudden increase in the cost of transacting in bitcoin. Here, again, it helps to get into the technical details for a moment. All bitcoin transactions are kept in a decentralized and public ledger. When someone makes a transaction with bitcoin, miners in the network solve cryptographic puzzles to verify and log it—and get paid a small fee in bitcoin to do so. That has given the cryptocurrency a scaling problem: As demand for transactions has gone up, the price to transact has gone up. Indeed, the price of a bitcoin transaction recently spiked as high as $55.
Dark web is a part of the world wide web that requires a special software to access it. one cannot find Dark Web in the normal web search engine. some sites in the dark web are explicitly hidden and can only be accessed if a person knows the address of the site. “Darknet markets” operate as special markets in the dark web that mainly sells illegal products like drugs and firearms. Dark web is completely anonymous and the use of bitcoin to access the services of the web dark is seemingly dangerous as the transactions cannot be monitored either. It cannot be tracked.