Resellers. Never to me (if that's the question/implication). I've had many ask to pay a premium on discontinued mods, but I stick to my word.
The rarest mod I've made only has about 15 production models and a couple prototypes made. That was the interactive IJ PoA rails. I discontinued it after about a month with nearly 50 on the list (was too time consuming and messy to produce), and have had well over 100 asking for them. Such mods are sought after and carry a premium second hand (a fun project for me, but a loss overall with about 300 hours into its development over several months [between 3 Pinsiders as I didn't own the machine, which dragged it out beyond what it would have been if I owned the game--I had to borrow rails to mold, ask for measurements back and forth, etc.] and fair expense for resin and silicone [3 molds made], but super awesome to see that it's desired by those that know it exists).
For RZ, the Spine mod has had demand inquiry around 3x what exists and I know has sold for a premium. This was discontinued before I released the Elvira mods--ever since then, everything I've ever made got a significant boost in demand (partially thanks to Zach's endorsement on SDTM for Elvira, ACNC, and RZ in Jan/March 2020).
I'm far happier to see others get a premium after they supported my mods than accept one myself.
If I ever saw anyone have to sell for a loss, I'd feel negatively self conscious, as if I failed to offer something of value.
Unfortunately this isn't the first time there's been some uproar about discontinuation that I attempt to defend. My JD Sniper Tower thread shows a few other public pushes I responded to. Otherwise, it's every few days I'm asked about discontinued mods (most accepting the fact and not offering a premium).