Problem with buying used is EVs you are limited to what is for sale now. Search EV market share by year in your favorite search engine, then do your own analysis: if you are buying a used car more than 90% of your options are not EV (even if we include PHEV)

If you drive a car then EVs should be your first choice, and they should be worth a premium over other types. However in the end used car buyers are limited to what is for sale now.