30%-50% loses for a well-used 15-year-old lithium battery seems reasonable. Depending on the charge/discharge cycles and depth of them, it can last a lot more or a lot less, see tables and graphs e.g. here:

https://batteryuniversity.com/article/bu-808-how-to-prolong-...

I think you have a pretty big misunderstanding if you think that electric cars are driven like petrol cars where you always charge to 100% and then don't charge until the battery is at 0%.

Your link has a graph[1] that indicates that while using 75%-25% charging states, which is what most of the electric cars use by default, you would get 10 000 cycles and still retain 80% of the original capacity. On a 500km range electric car, like that hypothetical Tesla Model 3, that would be 80% capacity left after 2 500 000km. You can Google quite easily that there are for example Tesla Model S cars with over a million kilometers driven.

[1] https://batteryuniversity.com/img/content/capacity-retention...

It's how these batteries work. We have decades of experience with Lithium-Ion batteries now.

EV battery lifetime has basically surprised everyone. They're lasting way longer than anyone expected. It seems this is mostly because most battery lifetime data was from 0-100% charge cycling, which is rare for most EVs, and cycling over smaller ranges with smaller duty cycles and slower charging (also the norm in EVs but rare in tests) makes a huge difference to lifetime (which was already known to some extent, but was not anticipated when EVs with large battery packs first came onto the market). In fact one of the reasons we don't have large-scale battery recycling at the moment is because there's still relatively few batteries even from this first generation which have reached the end of their life.

In fairness to the OP and your question, over the last 30 years, several brands of cars developed catastrophic engine and transmission problems in the first 100k miles and definitely 200k miles - and there are many irrational buyers that buy (or lease) new cars every 3-5 years or before 100k miles.

There are also buyers who are overwhelmed by simple maintenance (oil changes, brake maintenance, window regulator failure) that help get their cars into these states.

Luckily, evs require so much less maintenance, even these buyers are likely to be surprised.