[usrusr]

The reason you don't see "rocketship" investment is because the problem isn't hard enough, no matter how well you solve it you wouldn't be anywhere close to virtual monopoly. But despite that, hydrostor.ca got an investment of a quarter billion earlier this year, and they already started projects for A-CAES facilities in the GWh range (comparable to smaller pumped hydro) when their funding was less than a tenth of that (I suppose actual projects wouldn't be included in that funding, I think they see themselves as a project specialist, not as an owner/operator even if some/most/all current projects seem to be subsidiaries, perhaps a bit like spacex/starlink if you like space analogies).