Times have definitely changed. I can't make mix "tape" discs for friends anymore, because none of them have anything to play them on (including laptops). As for selling CDs, I figure I've bought them only for my pleasure, so never went into it thinking about resale value. Not sure what the "value" to a particular disc is anyway, if a listener can hear it on a streaming service. We actually have it better than film buffs - I can stream my music all over my house from iTunes on my computer, but studios don't even allow DVDs to be ripped to a home server. (Studios definitely need to make that accommodation, if they want to stanch the loss of DVD sales.)
I have an old iPod in my car, connected via USB. I load 20 GB of music on it, random, and love it; every couple of months, I change the music mix. My Subaru has a CD player, but I never use it. It also has SiriusXM; I find myself mostly listening to Little Steven's Underground Garage and Fox News.
If you've concluded your CDs have little-to-no resale value, why not give them away here? Not to some public library where people won't appreciate them, but offer them as "Pay It Forward" here, or trade them for other CDs. Might be a lot more satisfying to know they'll have a good new home.