My 4 cents:
OEM warranty costs are built into the price of the car. After market? I'm not so sure there's value of dealer specific offers.
As a current EV warranty on are basically the battery and the infotainment/OS screens and brain. All the gear related to charging should also be covered. Inverters and chargers can be incredibly expensive.
The rest of the vehicle is not subject to the same sort of wear and tear that running oil, coolant, and gasoline fluids through a motor will bring no matter how fabulous the filtration might be. How expensive can it run to service brakes, cooling fluid, lubricate rolling parts, replace wipers, tires, etc? There's not really a series of oil changes, retunes, etc.
P&C Insurance is a good thing. But for the rest, it's more like health insurance which used to be strictly for major medical like major life threatening surgeries, but got extended to covering everything else under the sun from pills to cosmetics. Costs went up to the moon. THe risk in warranties is exactly the same - using it as a prepay mechanism will drive it up as the incentive is to game the system. Play if you want to.
As to warranty value, IMHO, few are mentioning residual value. Look at Carmax for 4 series vehicles from 2017 and 2018 - 4-year old cars...I'm seeing asking prices of $25 to $26,000. I'm not sure what the 430's were going for new, but I'd guess the dealer's spread might offer $ 5,000 less to buy your car for resale. How's that translate into the unexpired warranty miles / years etc. ? Don't know. But I wouldn't get lost in the value of extending warranties for the purpose of the NEXT owner's enjoyment. Used car dealers want to sell warranties as much as the new guys... so how's that affect what they'll offer you when you sell? Dunno.
But as always, your mileage may vary. Have fun. Save money.... you're gonna need it right? Maybe feed the car less and go to the Bahamas?