That seems like a reasonable division into three strata. You could divide it into a lot more than three. Each movement upward leaves one set of problems behind and may introduce new things that would not have been realistic considerations before.

I'm 'average' in your classification, as are most people I see on any regular basis. What you've called 'poor' would describe the time I was unemployed or my college days but is now a fair ways away. What you've called 'rich' seems impossibly out of reach barring some unlikely windfall.

Within 'average' though, there are upward movements that would be nice. I've paid off all loans except my mortgage. It would feel pretty great to pay off the mortgage and not owe anybody any money.

I live in a moderately expensive city. It would be great to feel like I could just move somewhere more expensive like New York City or San Francisco if I wanted to, own a home, and take advantage of the opportunities there.

It would be interesting to see a description of many strata from someone who has researched this, and see what problems are solved and what people's main concerns are at each one.