I have read multiple literature from projects like those and they are all very similar. In the future, when there is overcapacity of renewables energy and the price is right, then it may become financial viable to operate the storage for renewable energy and sell the energy when demand is high. Until then however, for financial and practical reasons, they don't.
Snowy 2 is expected to come into operation in 2024. The key role, published on their website: System security and reliability – Snowy 2.0’s on-demand energy generation can respond within minutes to changing market needs.
They also have feasibility studies:
3. Commercial (omitted)
4. Business Analysis and Modelling (omitted)
https://drive.google.com/file/d/1A5ol58HEbqSaKG9D21CVGt-ntWx...
It will still be an interesting project to keep an eye on once it get online. If they can operate beyond doing grid system security and reliability, then it might become a proof of concept for renewable storage solution.
So do you got any source for a current operated pumped storage that buy renewables when supply is high, store the renewable energy, and then sell the supply when supply is low? If pumped storage for renewable is a solve and currently economical viable solution then surely a single example should exist? Rather than talking about FUD or "thread layers deep into the 1,543rd article", just link to an existing company doing pumped storage for renewable and be done with it. Do they exist or do they not?
If the answer is no, they don't exist but they may in the future then that is that. It is good that they try. It is good that they built infrastructure that may be used in the future for this purpose. Continue with the experiment and proof of concepts. With energy prices going up in many places they might very fast be working for this purpose, or at the very least replacing gas based generators that exist to create system security and reliability.