Source? For student loans at least, the amount of debt held is positively correlated with household income, not negatively like you suggest. https://www.urban.org/sites/default/files/styles/optimized_d...
> If wages increase with inflation, and if the borrower already owed money before the inflation occurred, the inflation benefits the borrower. This is because the borrower still owes the same amount of money, but now they more money in their paycheck to pay off the debt. This results in less interest for the lender if the borrower uses the extra money to pay off their debt early.
* https://www.investopedia.com/ask/answers/111414/does-inflati...
(The article mentions some benefits to lenders too.)
Not really, because inflation causes interest rates to go up correspondingly.
Lenders are not fools when it comes to inflation.
The "debasing of fiat currency" reduces debt burdens, and I would think that middle- and low-income folks are probably more likely to have debt (student loans, mortgages). A low-inflation or even deflationary environment is probably a worse thing for the non-rich.