It's not that simple.

Batteries are inherently more aerodynamic, because they don't need to suck in oxygen for combustion, and because they need less cooling than an engine that heats itself up by constantly burning fuel. You can getvincredible gains just by improving motor efficiency - the difference between a 98%-efficient motor and a 99%-efficient motor is the latter requires half the cooling. That's more important than the ~1% increase in mileage.

Also, the batteries are static weight, which isn't as nightmarish as liquid fuel that wants to slosh around in the exact directions you want it not to. Static weight means that batteries can be potentially load-bearing structural parts (and in fact already are, in some EV cars).

The math leaves out a lot of important factors.

Not to mention that jet planes routinely take off heavier than their max safe landing weight today too, relying on the weight reduction of consuming the fuel to return the plane to a safe landing weight again while enjoying the extra range afforded. This trick doesn't work well with batteries either.