After some googling I actually can't even find a place to buy replacements so I can price them (maybe I'm thinking about this wrong?) For a car, $4k sounds low enough that if it doesn't work out it's not /that/ big a deal. These used EVs sound great for someone that just wants to try the idea out without becoming totally invested.

My point was that these are 3-year-old cars, most with light usage. It's easy to find examples with 15k miles. The packs have held up very well - mine had lost at most 5% of its range, if that. So, assume 22kWh capacity left, that should be worth $4k alone by the author's metrics.

it weights 1/3 of tesla so it degrades 3x slower

What has the weight of the battery to do with degradation speed? It is the cycle count which determines battery aging, and for the same distance driven, a Tesla has far fewer battery cycles than a smaller vehicle. The energy consumption of a Tesla is higher than that of smaller vehicles, but by a surprisingly small amount, as kinetic energy can be (partially) recovered. At highway speeds, a Tesla even sometimes consumes less energy than some smaller EV due to its better aerodynamics.

weight of vehicle.

battery degradation is proportional to energy x time. if you need 3x more to push all that weight, is it is dead 3x earlier.

it's just like how you waste breaks 3x faster breaking a cayenne instead of a sedan.