I agree the middle class is almost invariably the engine of a country,

Certainly. And not only of a country, but also of an entire human ecosystem no matter how small or large.

...are oftentimes geared towards localized growth rather than country development.

Yep! that's right. Isn't this 'anomaly' a pretty interesting one as indicator of Human Evolution?

The wealth of the middle class is generating momentum due to their larger footprint and comparably significant spending capacity, so that's where one should be looking at.

Elementary! Without an increasing big mass of docile & dumb consumers who blindly consume everything with no questioning, the richest wouldn't have enough blood, sweat & tears to squeeze as to be able to build a profitable bizniz. According to them, I suspect we actually need some kind of aspirational social class, of some sort, all the time, to keep 'this current world' spinning. Isn't it?

How the middle class perceives themselves can make a big difference in the kind of motivation that is directing this momentum, either towards development or devolution.

Mm-hmm! so, what's your conclusion?
Is the Middle Class perceiving themselves nowadays like a Poorer version of Rich or like a Richer version of Poor?

Thank you for your thoughtful comment brother! :)