All kinds of deposit and government bond interest rates should be charged in tiers to ease the gap between the rich and the poor.

Old money of 10 billion enjoys a 2% interest rate—just lying back for a year yields two hundred million.
An ordinary person who deposits 1 million earns only 20,000 in a year; a hundred ordinary people saving hard can’t match one wealthy person.
Every year there’s inflation and money printing—and in the end, it all gets collected by the richest people.