system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the existence of a middle class important in assessing the strength of an economy?

Is it because they spend their money while having some saved up in case there is a downturn? Or is it something else?
gpt
That's a big one, yes. Compare an economy where there is a middle class to one where there's only very rich people, and very poor people. How will the economy continue to perform when the poor masses have little to spend to fuel it, and the few rich even though they can buy a lot probably won't do so, purchasing only what they need in terms of necessities and perhaps hoarding money instead of spending?