Imagine all of humanity in a skyscraper: the poorest live in the basement, middle classes in the middle, and richest in the penthouse.
The tower is a work in progress; as we add more floors, people move up in wealth; however, this construction creates toxic sludge which slowly fills the lowest levels, killing off the poorest.
Lots of people argue about how fast the sludge is rising, we have only the roughest estimates of that rate or the number of sludge-killed poor.
On an individual level, we strive ever higher lest we drown in sludge.
Collectively, all levels do not want the sludge to reach them; what happens when one level decides to drill a hole in the basement that will likely drain sludge and unfortunately damage the foundation?