"large numbers of the birds are bred and released to become road kill so that rich folks can kill them for fun"

They become "road kill" when they are hit and killed by vehicles on a road. Killing them once they are dead wouldn't really be much "fun".

Yes, pheasants are bred and released for rich people to shoot at, but it is still quite possible to find feathers without any deliberate killing involved (some may die of natural causes, and some will be killed by foxes, who may or may not then eat them, but who also don't usually eat the feathers).