You're free to define words as you please, but it gets in the way of having a good conversation.
What you call the lower economic class is better known as the precariat. Those who have low income, no wealth, no meaningful social safety net, and no opportunities.
What you call the upper economic class is better known as the independently wealthy. Those who don't need to work at all in order to live well.
I don't think you can meaningfully talk about an "economic class" that is purely a function of one's wealth, income and expenses, which is why sociologists never do.
What you call the lower economic class is better known as the precariat. Those who have low income, no wealth, no meaningful social safety net, and no opportunities.
What you call the upper economic class is better known as the independently wealthy. Those who don't need to work at all in order to live well.
I don't think you can meaningfully talk about an "economic class" that is purely a function of one's wealth, income and expenses, which is why sociologists never do.