Because we've been working pretty hard on batteries pretty hard for over 200 years, it will take a 10-20X improvement over current technology and we're not really seeing anything that is exponential like that anytime soon. I mean obviously it could happen, it's just unlikely given the past 200 years of steady improvement and not step function improvements.
We use enourmous amounts of energy and we invest enourmous amounts of money in energy production. At the same time we have neglible storage and and neglible investment in storage.
some numbers:
194MWh - capacity of Hornsdale Power Reserve in Australia