A couple of quibbles, partly_warmer:
There definitely are pirate historians; I read a book last year called Under the Black Flag by David Cordingly, who has written a number of books on pirate history. I will therefore now declare myself the Armchair Expert and repeat a bunch of stuff from the book, hoping my memory is accurate.
True, people would get dispensation to attack other ships at sea; these people were typically ex-Navy types, and when acting in this capacity they were known as “corsairs” or “corvairs,” I forget exactly. Most pirates in the 1800s, though, didn’t bother; they were either young criminals who went to sea for the (substantial) amount of money they could make, or ex-Navy or Merchant Mariners who were on Navy ships that were taken by pirates. Many of the sailors would simply join the pirate’s crew when this happened.
Also true, aside from the fact that they were sailors and so needed extensive vocabulary about things that were particular to ships, and that were particular to pirate lifestyle. Most of this they would probably have learned in previous careers as legitimate sailors, but I’ll bet there was linguistic change going on constantly as new sailors (who often did speak different languages) joined the crew and old ones died/left/retired.
And yes, there were a number of pirates who retired as prosperous landowners, including one whose name escapes me, darn it, who owned a huge chunk of Jamaica that still bears his name.
That book linked above is a really fascinating read, if anyone is interested: factual, extensively researched, and rarely slowing down into those dull passages that are usually the hallmark of academics’ writing.