Been there, done that.
WORKERS OF THE WORLD, UNITE!
YOU HAVE NOTHING TO LOSE BUT YOUR CHAINS!
A scam that merely replaced one set of rulers with another, aka the Nomenklatura.
But to answer the question, I would define middle class as people who have substantial property (e.g., a house and a stock portfolio), but not so much property that they can stop working and live on their interest, dividend and/or rent income.
I would define the rich class as those who do not have to work, and can live very comfortably, perhaps luxuriously, from their assets.
I would define the poor as those who have little or no property, and who must live paycheck-to paycheck for a relatively low standard of living.