Use EV as “harvester” at night, sell back at peak demand?

So….

1. I “harvest” electricity into my EV when the rates are cheapest. Night, presumably. Or just let the charger watch the price and start charging when it’s below a certain value.
2. Sell the electricity in my EV back to the grid at the high demand/high cost afternoon demand.
3. Profit?

But why use an EV? Just a “powerwall” or other battery storage system.