Fair question. EV batteries do suffer degradation, it’s to do with the nature of lithium. When it allows electrons to pass through a vein is formed in the substance, it looks like marble and over time these veins become larger and the overall capacity of the lithium is lower. This happens in all lithium. In an EV you need a higher grade, more expensive substance because what driving requires is instant power to the drive train for longer so it’s not like a laptop battery which is lower grade. There have been teslas doing over 1 million miles and suffering lower degradation, and current models of EV other brands are seeing a few percent per year in a heavy mileage year. In practice this translates to a minute extra charging. It will take decades to get into a situation where you can’t go anywhere but you’ll most likley have changed vehicle by that stage, if the average ownership is 5 years.

But that is the fuel, not the motor. The motor has almost no moving parts, a petrol motor has lots more and is generally a complex and over engineered solution to move a drive train by comparison. What you are saying is that petrol doesn’t go off, it does and that it’s a preferable fuel - it just isn’t by any measure. Repair and maintenance of electric motors is far easier and cheaper, and motors last a lot longer.