I had to dig a bit, but I found out the source poll's threshold for "middle class": 200% or more past the poverty line.
The poverty line is about $15k for individuals. People making $30k a year are, clearly, not middle class. The current standard puts the beginning of middle class in the low $50k's.
A small amount (obviously less than we've had recently) of inflation is actually ideal. Deflation incentivizes literal hoarding of cash, instead of spending it on things, which is a very reliable way to bring an economy to a screeching halt.
No offense but this is exactly the belief I was being sarcastic about. The economy wasn't halted before Nixon introduced inflation as we know it today. And "the economy" at this point is practically a euphemism for rich people getting nearly the entire surplus while destroying the environment.
Please stop spreading this dangerous misconception.