ELI5: How do ‘adventurers’ fund their lives?

For clarification, I understand that there is a whole class of elite that can do this with family wealth. Let’s get that out of the way.

More specifically, I was watching the documentary ‘Dave Not Coming Back’ (highly recommend BTW — can watch for free on Pluto). It’s about deep cave divers…and I’ll leave it at that so as to not spoil the plot.

What struck me is — how are all of these guys able to afford such expeditions? I can’t imagine having a 9-5 and then magically being a cave diver on the weekends. I was looking for instances of sponsorships or similar, but I couldn’t find any. Finally, a wife in the film says something along the lines of “if he couldn’t dive, I don’t know what he would do with his life.”

I can understand climbers on Everest getting sponsorships by The North Face or similar which allows them to pursue their expeditions and bring home enough bread so that they can live moderately well when they’re home.

But the guys in this movie…with all of their dive equipment and transportation and team they build…not to mention nobody could do this with a regular 9-5 I just don’t get. The only logical explanation is that they are funded by the government. But even that sounds unreliable.

Anybody have any insights how these non-sponsored adventurists/non-trust fund types fund crazy expeditions?