What an absurd position. First off, risk isn't the goal, reward is. Risk is just the price of increasing rewards. But we shouldn't mistake the two, or valorize risk itself. Any high risk business not taking risk mitigations available to it is a poor one. And any investor who isn't using low risk, uncorrelated assets to juice their returns is missing out!

Secondly. Bonds are not assets that "do nothing for no one;" they don't sit there in a vault. They are a loan to busineses, and they allow businesses and governments to build factories, bridges, and even other companies. They invite additional capital into the market, which can be used to make more high risk / high reward investments, for a small cut of the rewards. Even savings is a loan to the bank, which recirculates the money with their own loan desk. Negative interest rates in Germany aside, very little money in the system sits in an idle 'pile of gold.'

And that's really the problem here -- electronic deposits with the ECB cost banks money, so they're not using the central bank. The money still exists, and economy is still moving, but the normal holder of cash deposits is charging instead of paying for it. This is why it was theorized that 0 percent was the lower bound on interest rates, so it would be a more surprising outcome if this sort of thing didn't happen.