Unfortunately bitcoin is often used for illegal activities including terrorism and itt anonimity contributed great deal to that. That is the reason why bitcoin had bad reputation very long time, some even considered it as a criminal currency although every currency in the world could be used for crime.
Bitcoin is the crypto for darknet lite users at this point, there's a ton of other cryptos that are far better are keeping their users completely anonymous and move money a bit faster than what Bitcoin can do. Most criminals using Bitcoin still are just looking to exploit a lot of users on the surfacenet, such as ransomware producers or the like. I rarely hear of anyone using BTC on Silk Road anymore, but that's just anecdotal.
In the criminal world, as in the real world, the dollar is most used. The cash. Bitcoin is used very rarely. Still few people (and terrorists) know about bitcoin