Inflation is caused by inflationary currency. Any other inflation caused by supply chain issues, corporate greed, lack of market competition, etc is just added on top of that. Fiat inflationary currency is a rather new invention in terms of the human timeline. They aim for 2-3% inflation in "good years". Central banks are not to be trusted.

Think of it: in the last 50 years, everything has gotten cheaper to produce thanks to increasing mechanization, outsourcing to cheap labor/low regulation countries, and extremely efficient supply chains. Yet so many things "costs more" than it did 50 years ago. Even basics like bread. How is that the case? Shouldn't it cost less? Where is that "extra efficiency" going if not to lower prices? The answer: bread is the same value it's always been, the money has gotten less valuable. This is how they keep working class people running on a treadmill, never able to achieve economic mobility.

Inflationary currency devalues the currency you worked hard to earn by increasing the supply. It hits the middle class the worst because they have more of their net wealth in cash, often in the form of emergency funds, savings, and putting together enough money for a down payment on a home. Rich people have their money in assets which aren't harmed by currency inflation. Poor people live hand to mouth. If you want to identify the causes of increasing wealth disparity, the inability of people to save money is a major one.