What affect would mass-saving have?

Just a curiosity, I know nothing about economics.

Sometimes I get the feeling that not only have many upperclassmen hit personal economic escape velocity… the upper class as a whole may have as well…

I.e. if, say, 70% of Americans started saving crazy, like %50 of their income, living as bare bones as possible: would this have any impact whatsoever on elite society? Would it just… hurt the middle/lower class?

I'm tempted to say our lack of power relatively speaking is owed more than many realize to poor saving habits of the past decades, and we may be past the point where we can no longer meaningfully affect large parts of the economy with our saving anymore (yes I know many factors made saving harder, but it certainly also seems like behavioral changes on top of that which caused a negative spiral). My thought is that middle/lower class having a greater mass of cash reserves (not investments) means less money for the rich to play around with and less impulsive/reactive behaviors by savers. Also, greater sense of security which can have a butterfly effect of social, health, skills and other benefits.

On the other hand, maybe the economy "flows" better when people are loose. Maybe locally prudent spending behaviors end up making boom/bust cascading failures more likely.

Regardless, it feels like so much… I'll call it, "imaginary value" (I hear talk about this especially around AI, I just don't have the memory or familiarity to word it properly)… has appeared that the upper-class could almost have its own detached economy which isn't bothered by winds in the lower classes. Maybe that sounds obviously true or false, I don't know.

But the main question which would be cool to get a knowledgable persons ideas on in some detail would be that first question. How would sudden and massive changes in saving behavior affect different parts of the economy in the short-mid term?