My guess it has to do with ambition.
I'm not sure where ambition comes from.
Maybe circumstance.
Someone who grew up with nothing might be ambitious to accumulate a lot of things.
While someone who grew up with a lot might just be happy to maintain.
I think it might be easier to describe how to become successful than to determine why some people try and some don't.
Probably the people that succeed and accumulate a lot have a written plan.
And those that dont, dont have a written plan.
But the question is why do some have a written plan
and some do not?
I guess some just don't care.
Some are content with less.
Some are secure with less.
And some are insecure so they need a lot.
Also before they had all the designer diagnosises back in the 60's and 70's
if a person was greedy, jealous and unthankful, people would just say, "He is an axxhole".