It's all about collecting, nothing more. People will obsess and collect the weirdest things, funeral stuff, old signs, glass bottles, why not electronics? The Amiga had maybe 5 million sold total, most of that has long ago hit the dumpster so it's rare enough to be collectable.
I suspect it will only increase in value if/when C=USA cheap cr@p hits the market, because then the name will be better known..