Earlier quoted context omitted.
Where does this myth come from? Looks it's about 10% battery degradation after 200K miles. Tesla is rating their batteries for 300K to 500K miles. Most American company ICE cars are scrapped by then. Not to mention all the ICE related maintenance costs over that time like oil changes, transmission fluid, timing belts, hoses, etc. etc. You can look at 6 to 10 year Model S cars.
It's not a myth at all, and Tesla's "rating" is a lie. Look at data on Prius battery packs and what Toyota rates them for(100-150k). I understand I'm comparing a hybrid to an EV, but there is much more data and I actually trust Toyota. Buying an EV with 100k miles and the original battery pack for 20k is a bad idea.
The Prius battery is far smaller (about 5-10x smaller) than a Tesla battery, so it is cycling charge / discharge far more often.
So you'd expect the same quality battery to last 5-10x less miles in a Prius than a Tesla driving the same distance. It's likely that Tesla's investment in battery quality and active temperature controls mean the Tesla battery is also treated better and higher quality.
Topping that battery up with a generator in the Prius complicates things, both reducing kWh used per mile (some from generator) but also allowing a discharge - recharge cycle to occur multiple times in the same trip.