We're also pretty far away from the kinds of renewable penetration where you actually need a lot of storage, so we have plenty of time left to build more batteries and electrolyzers.
It's not just a means of energy storage; it's a method for producing a vital chemical feedstock. If your main alternative is processing natural gas, building more electrolysers is a no-brainer. You'll have to do it no matter what the efficiency, since we just don't have a better way.
80 per cent is what you call extremely inefficient ... what percentage would be "efficient" then in your opinion?
> Accounting for the accepted use of the higher heat value (because inefficiency via heat can be redirected back into the system to create the steam required by the catalyst), average working efficiencies for PEM electrolysis are around 80% ... [https://en.wikipedia.org/wiki/Electrolysis_of_water#Industri...]