Agreed, but would the hackers risk a big dump on some exchange/s which would quickly be raided by FBI CIA et.al. given they will move heaven and earth to stop the release of these 18,000 documents and to get these guys.
If the amount they're asking for is not that big they could easily use a mixer or trade it for altcoins to hide their tracks then dump it on an exchange.
On another article it's mentioned that they've leaked episodes of orange is the new black after they received the ransom. It's probably not a good idea to pay these hackers since they could still delete the files afterwards.
The news is the latest public extortion attempt from the group known as The Dark Overlord, which has previously targeted a production studio working for Netflix, as well as a host of medical centres and private businesses across the United States.