Go out to 10-year Treasuries and the inflation adjusted rate of return currently is a flat zero.

FORBES: Savvy Investors Survive Fed's Remorseless Abuse

Series I bonds consist of two components: a fixed interest rate return and an adjustable inflation-linked return, making them somewhat similar to TIPS. The fixed rate never changes, but the inflation return rate is adjusted every six months and can also be negative (which of course brings your total return down).

FORBES: How to Find Low Risk, High Return Investments

In a world where annual inflation is running at a 3% rate (actually more if you think for a moment about your rising healthcare and educational costs), there is an overwhelming demand for a security whose rate of return is a negative real (inflation-adjusted) rate of 3%.

FORBES: Negative Treasury Bill Rates Are On The Way

After all, it you are satisfied with a 2% rate of return, near zero adjusted for inflation, go ahead.

FORBES: Managing Money