It’s $0.22/kWh in SF proper so 100kwh (max charge largest Tesla)X.22 is $22 worst case. No idea where you are getting your numbers from mate. It’s always going to be cheaper to use electricity than gas.
Well, i had the same belief that battery needs to be replaced in 10 years max, there is a guy who uses his tesla as a premium taxi and had driven 100k miles( not sure if it was 100k or 200k) and his battery capacity had reduced by only 5%.
Also even the phone batteries are good for about 1000 charge cycles, and at about 250miles range thats about 250k miles. So that's pretty good amount of miles before you would need to change the battery