There aren't enough batteries in the world to recoup any significant chunk of this lost/free/extra energy.
Power plants will sometimes even pay people money to accept the electricity, because too much of it has the possibility of damaging something.
As solar and wind grows, we will use more pumped hydro, but there won't be / can't be e.g. a tripling of it.
If free energy needed to be expelled and couldn't be stored for some weird reason, it could be used to grind wheat, purify water, or run scientific computing to contribute to curing diseases rather than attempt to acquire speculative database tokens.
This is not "some weird reason". Thus is how the current power grid works in many locations.
If your theory was correct, then negative energy rates wouldn't even exist right now. But they do.