I think a better analogy would be a cruise ship vs tramp steamer. You can book
a cruise on a large scale reputable ship and go around the Caribbean or the
Mediterranean. Or you can book passage on a smaller tramp freighter (with the
attendant questions of food and hygiene) for a week on the same cruise.
There are not a lot of people who choose the latter, but the ones that do are
the more adventurous type and claim it was the best time ever. Crew was great,
food was awesome (and local), got to see sights the tourists miss, etc.
I do think the tramp freighter passengers are not your normal people, but I
don't think they're quite as off the deep end as you imply.
I was on an afternoon catamaran trip and the skipper was a Brit (trained by the British Yachting Association or something of that sort). He was on a world circumnavigation but had settled in the Dominican Republic because the Panama canal seemed like a big step and the Asian Rim can be kind of dangerous. People found out he had lots of experience and constantly had him piloting vessels for rich folks or for tourists - enough to eat and have beer money. He had a bunkie whom he enjoyed spending time with so life was good.
We talked about what I now think of as a few 'free trader' or at least planetary excursion type scenarios:
Some people carry firearms aboard. Of course, as with all things in nature, the ports you'd most want to be armed in will confiscate and lock up firearms. But they might be of use between ports.
So, it's getting dark. You hear the sounds of a bigger diesel overhauling you from behind. You look out at the oncoming launch and realize the ship side facing you is full of men with face masks on. You can't see if they are armed. Do you start shooting? (Maybe, but you'd be wrong. The were fisherman wanting to see you some fresh fish. They wore the masks for UV protection.)
and
I asked our tour skipper about the sorts of things he'd seen driving the tour boat. One day, about halfway between the DR and a small island, his entertainment organizer (a wonderful lady) came to him and said (very quietly) 'Skipper, we got a problem. We got a box of pineapples. When we opened it and three or four hand sized tarantulas jumped out. We're looking for them....'
The skip said he told the crew to unobtrusively look in likely shady hiding spots (in couches, under cushions, etc) and coral or take out the spiders. They eventually got them rounded up without the passengers knowing. The skip said to me "If I'd have announced we had 4 missing desert plate sized furry spiders with a nasty bite running around the ship, I'd have had "Crew Overboard" in all directions in the mid-ocean...."