The way I'd tell it is that owning the Bolt adds less than $20 a month to my electricity bill. Prior to that, I spent much more than that at the gas station. I also had to go to the gas station, instead of just plugging the car in when I get home.
Here's the calculation. In 2018, we drove our Bolt about 7500 miles, and the Bolt claimed to use about 1750 kWh. Charging the Bolt, we used about 100 kWh at paid chargers, costing about $27, and about 1850 kWh according to my JuiceBox Pro (which includes doing things like preheating the car). I pay $0.12 per kWh, so it added $222 to my electricity bill, or less than $20 a month. Overall, charging at home cost us about $0.03 a mile. Charging at paid chargers cost us about $0.07 per mile (although it varied a lot).
A Prius getting 50 mph is also about $0.07 per mile at $3.50 per gallon. My Golf TDI, which I consider to be a comparable car, got about 32 mpg for my (mostly city) driving, so that's $0.11 per mile. My TDI would have cost me $820, so I saved about $570.
But it's not really about the fuel-cost savings. It's about never leaving the house in a car with a nearly empty tank. Never saying “oh crap, I forgot, I need to stop for gas, now I'll be late”. And it's about being fun to drive while not spewing pollutants everywhere I go. And a smaller carbon footprint is nice, too.