Ok you're arguing that there is no such thing as a liquid store of value that that offers a better return than a negative yield government bond?

So let's say I'm a bank with a stack of 1B in high denomination central bank notes. I calculate the rate of return as zero minus the annual cost of securing those and the annual risk that they are stolen or destroyed. Inflation isn't a factor because the bond is in the same currency. Based on your explanation that rate of return will be lower than the -0.11% that I would get from a german 30 year bond today. And there's simply nothing I can exchange those central bank notes for that would do any better than the bond.

Like OP I've never understood negative yield debt and I'm trying really hard to.