To oversimplify, it’s a metaphor about what it’s like to go through life relying only on your senses and not using reason to question or analyze the deeper meanings behind your surface impressions. The story goes on to discuss a prisoner who escapes the cave and gets a taste of true reality, that prisoner is meant to represent a philosopher. When the escaped prisoner returns and tells the others of what he’s seen, they reject his claims saying how absurd it would be to believe that there’s anything more than just the shadows. I think in this day and age it’s easy to guess what that interaction represents, but Plato had a particular bone to pick about this since his mentor had essentially been executed for questioning various things.
https://en.wikipedia.org/wiki/Allegory_of_the_cave?wprov=sfla1
Well it does seem to be talking about the global 1% which is known to include a pretty big slice of the population in relatively wealthy places like the US. The more exclusive 1% that people usually talk about is the US 1% or the 1% of another specific country.
Keep in mind that 1% of 7 billion people is 70 million. And estimates for the number of billionaires in the world look to be under 3000. In addition, most estimates for worldwide median individual income are under 3000 USD per year.
Taking all that into account, 140k sounds pretty reasonable as a boundary for the global 1%.