I don't think batteries degrade that much that fast. I would imagine it's akin to gas cars, where you lose about 10% or so in efficiency after you put on a lot of miles, like 100k. (My EV6 seems to be as efficient as when I bought it in 2022, but my driving style is all over the place, so it's hard to measure from one charge to the next if I'm feeling a bit spirited in my driving that day)

Are you sure about that? If you go only uphill in a gas car you will use a lot more fuel per km, just like an EV.