I read recently that France is selling bonds at Negative Interest Rates. I understand why this is beneficial for France, but why in the world would I pay money to let someone hold my money?
The simple answer: Because you believe every other option can yield greater losses...
So the thinking is; Lend it to France you'll get your money back. Put your money in a bank and there's a chance you won't get it back if the bank goes bust.
Investors also believe that rates will continue to go more negative, in which case they will actually MAKE money. It's a momentum play which will eventually reverse but since the Bond market is extremely liquid, it's a bet that can quickly be unwound.
Another theory floating around is that if the weaker countries of the euro leave (e.g. Greece, ect...) and the core keep the euro that the value of the euro will actually rise. So by putting your money in French or German bonds you would also be securing cash in French or German euro's. - Thinking the unthinkable on a euro break-up - Gavyn Davies
The only reason I can think of would be if you were convinced that you couldn't hold on to your money. Treasury Bonds are often viewed as very safe investments, and often used in some situations where cash isn't appropriate.. Also, they typically have a somewhat patriotic theme, helping your country to grow. In addition, many people don't really pay attention to the rate of the bonds, but are just investing in them. The more people investing in them, the lower the yields become.
But the bottom line is, I would invest in a savings account any day over a negative interest rate... And it looks like I'm in good company as well, a quick study of reports seems to indicate that these are a very bad investment...