In a previous post, I went over the math behind the electric car battery scam, but math loses most people, and the idea of rechargeable batteries also escapes most people. They don't know lithium ion batteries wear out because they've never kept a phone for more than five years. The only rechargeable battery most encounter is the $100 gasoline car battery we replace every 5 years or so.
The best way to think about rechargeable batteries (any of them) at the electric car scale is to think of them like car tires. Everybody knows tires wear out, somewhere between 20-60,000 miles and, in general, are very expensive to replace. Everyone remembers the sticker shock of buying their first set of four tires. Electric car batteries wear out at about the same pace, 20-80,000 miles, except they are nearly ten to thirty times as expensive as tires (by the way, you still need to buy tires too). Some 'after market' 'used' replacement batteries for the Prius start at $500, but typical is around $5,000, a tough purchase for a 5-10yr old car. Tesla, with a much bigger more expensive battery, can touch $20,000 to replace, again, a stiff repair bill for any car. But it's 'baked into the cake' and, in a way, may be where Musk plans to make his next fortune... replacement batteries.