They likely have a better implied return than Treasuries and many corporate bonds though, and people invest trillions of dollars in those. Risk-free investments

They likely have a better implied return than Treasuries and many corporate bonds though, and people invest trillions of dollars in those. Risk-free investments that beat inflation aren't easy to find. There are some issues with postage stamps as an investment, though. They're not as liquid as T-bills, though if they become a popular investment that problem solves itself. More worrying is that the USPS is not quite as reliable a borrower as the US federal government - can you really be certain this would never lose value? I'd like to see where the bond ratings agencies would rate USPS stamps.