Mostly they are just involved in a business with a vast amount of money at stake and if they are astute and/or luck out, they will be able to rake off a tiny proportion of the money involved which is nonetheless a large amount of money. If they pull this off, you may hear of them. If they don’t, you won’t. Your perception is therefore heavily biased.
For every Onassis there is a Captain [Cough] who gets into the business and goes bust. I’ve had a number of people like Captain [Cough] as clients over the years. He was a London Indian. When I was working for him he owned a few ships, was always looking to trade up and was doing pretty well. I lost contact with him a few years ago but then heard from my old employer that he had lost everything that he owned. Then there was Captain [Achoo], a Greek owner who started out in ferries. We did a lot of work for him, not least of all because of his fleet of four ships, three were under arrest to creditors and the third was, umm, well it was in a pretty sad situation so singular that I won’t mention the details because they might be identifiable. Then there was [Ahem] a Pakistani guy, and his son. They were relatively wealthy upper class professionals who decided they were going to put their life savings and retirement money into buying some seriously old tonnage. They managed to pick up a couple of voyage charters and get through them (somewhat miraculously) without anything going majorly wrong. They had won the lottery. They went from (relatively) smalltime chancers who had gone into a risky venture to swaggering millionaires almost overnight. Then on the next voyage the wheels fell off and they lost it all.
I have a few more examples but you get the picture.