I agreewith the fact that it's easier for them to use crypto to buy weapons or something like that in the darknet. But before people started using crypto terrorists could use USD or other fiat. So, I don't like when people blame crypto as one of the ways which makes terrorists' live better.
That is the fact, all goods or tools will become instruments of crime depending on who uses them. It becomes more effective if it is increasingly difficult to trace and complicated. Being fun for criminals.
We should just take the positive side and ignore it. The important thing is we can use this for good, to support the family, investment, and other useful things.