Didn’t expect the really colorful vibes

I showed this image to my friend who knows zero about anime and asked him what he thought these guys did as a profession. Even after pointing out the skull and crossbones he refused to belive that they are pirates. Maybe I should introduce him to the Netflix series first…

I really don’t get this anime. Are they in the future now? Are they in space? Is he the king of pirates now? Did they get the treasure? I’m not saying it’s bad or anything, I’m just terribly out of the loop and I guess it’s too late trying to catch up.