I can tell you what I have seen, not anything at all imagined.
I have seen hundreds of people quit their jobs in third world mines and other "western owned slave labor". So I can tell you first hand exactly the outcome that happens.
I have seen those people go back to growing their own food, making and washing their own clothes, building their own houses etc. They go back to being members of their communities. They have massively more food and water than they need, and quickly have a lot of social time. Now they have time to spend with their family and friends. They don't have much money, so often they won't own a car, but they have plenty of food and water and shelter and family time.
Their basic needs are met, and they have a good life.
Actually, it virtually all of the 15 countries I have been to in West Africa I have met hundreds and hundreds (and seen thousands) of people that have massively more leisure time than anyone I know in the Western World, and on the whole I would say people are happier. Certainly they have no stress, no timelines and don't answer to any boss. They have no alarms, and don't care what time it is on any given day (or what day it is).
This is not hollywood. This is not the world CNN tells you it is. Child soldiers and prostitution are not the only option, and in my experience in over 30 undeveloped countries, they are extremely rare.
You say that people who stop doing this back-breaking, underpaid work end up better off. If that's the case, why are people still staying on the shitty job? Why aren't they making what looks like a no-brainer decision from our viewpoint?
Of course, the lure of "lots of money" is a strong one, and they will work for years and years thinking one day they will have the lucky break that will make the difference and pull them out of poverty. (side note: sound familiar? Look around you)
Like I said, read grapes of wrath to see an excellent account of how people head towards this "working dream" only to become disgustingly trapped working as slave labor, continually going backwards even though they work harder and harder. When they are unable they are kicked out to die and replaced.
And finally, many people do quit and attempt to get away from it all, but there is an endless stream of naive newcomers to continually staff the mine. (again, see this clearly shown in grapes of wrath)
Thanks for the explanation. Those may not be good reasons, but they're understandable reasons that help solve the puzzle for me.