I can't find any reliable numbers but I doubt the median is substantially different than the mean in this case. 500k sounds like "a lot" until you consider that 17+ million cars are sold in the US every year.
Again, this just isn't true.
With the tax credit a Chevy Bolt can be had for under $20,000, less than a Corolla with similar utility. A Model 3 can be had for under $30,000, which is more or less exactly equivalent to the volume trims of a Toyota Camry, the most directly comparable car. A new Model Y can be had for ~$34,000, a few thousand more than the volume trim level of a RAV4.
All of those are before operating costs are considered. In December 2023 there are available affordable electric cars at any definition of "affordable" when talking about a new car.
Yes, the temporary demise of the Bolt will limit EV availability at the very bottom rung of the new car market in 2024. But the general premise that the "vast majority of the population can't afford the up-front costs" is simply not true (at least if we're scoping "the population" to people considering a new car in the first place).