Germany attempted to test appetite for safe haven assets and failed

Ten years was a good investment when we are talking about Bond. What about 30 years? Usually yield are tempting. Not any more. Germany's historic 30 years auction failed. Record-low yield of -0.11% resulted with demand of €0.869 billion way below €2 billions target. Who buys Bonds?

https://www.reuters.com/article/germany-auction/germany-sells-30-year-bond-at-auction-with-negative-yield-for-first-time-idUSS8N25A01F