Great idea to napkin math it, but I think you're off by a very large margin. CA energy commission shows PG&E's energy consumption to be over 70,000 GWh.
$2,500,000,000 profit/70,000,000,000 kWh consumed is ~$0.035 per kWh.
So not exactly the smoking gun that CA ratepayers are looking for.
This is based on total electrical energy production of 17,301 GWh, since PG&E doesn't seem to publish their total distributed energy.
https://www.google.com/search?q=%242.5+billion+%2F+17%2C301+...
https://www.eia.gov/state/print.php?sid=CA#tabs-1