One other thought on I Bonds...
the US Treasury sets the fixed rate portion (at their sole discretion, they do not disclose how they decide.) They use a publicly disclosed method of calculating the variable rate portion, based on CPI-U, reset every 6 months. There is no cap on the variable rate portion, so, hypothetically, if we have runaway inflation in the CPI-U, the I bonds will compound at that inflation rate, increasing every 6 months. To that extent, an I Bond is a hedge against inflation, backed by the full faith and credit of the United States.
Surveys indicate that the public does not expect inflation. Many commentators are of the opinion that the bond market is signaling a recession ahead. It is hard to find a commentator who says savers need to prepare for runaway inflation in consumer prices. However, since August 15, 1971 the global monetary system has consisted entirely of fiat money. The purchasing power of fiat money (US Dollars and all others) steadily declined. Permanent inflation has been generally accepted by central banks, such as the Federal Reserve. Central bankers say they are not content with "disinflation" less than 2%. The "Great Inflation" of the 1970s was characterized by double-digit annual increases in the CPI. I cannot say with certainty that the CPI will never again increase at double-digits.