its loving stupid because all of these games are probably out of print
and yes i know virtual console exists but thats only a small portion of their game catalog
100% correct
A large majority of these old games aren't sold officially. No, Nintendo isn't seeing any of the $300 from that copy of Path of Radiance that you bought off of some random dude on eBay.
Nintendo does have the Virtual Console but even that is on hiatus on the Switch and the support for it has been dwindling down since the Wii. There's still a multitude of games that there is no way of buying officially if you wanted to and dumping your own cartridge is far more complex and requires different tools compared to ripping a CD/DVD.
Dumping isn't necessarily a practical option for most people and currently there is little effort by Nintendo to make an official way to buy them. A lot of games (not all of them mind you) effectively in the same state as abandonware. Nintendo fully has the rights to do this obviously, but they aren't gaining much from this action honestly.