To be clear, electric vehicles are not a silver bullet. In cities, bikes are often the better option. However, they do save carbon, and as such, they are one of the many puzzle pieces of the big puzzle that humanity needs to put together in order to survive as a civilization. There will be no single solution because it is such a devilish complex and widely ramified problem. For a matter of survival, we need to grasp every puzzle piece we can.
Also, emissions from cars are a surprisingly large proportion of individual emissions - much larger than many people are aware of. They are like 120 Grams per kilometer per person. If you drive a combustion car to a supermarket nearby to get a pizza, the CO2 cost of the travel there will likely be higher than that of the food.
Edit: typo