If the owners are not dead but the amulets are being traded, then the amulets are not lucky.
Perhaps those previous owners, you know, the ones who did not die, consider that to indicate that the amulets are lucky, that's how they are able to sell them on. You've got a bizarre idea of what being lucky is, myself, I consider not dying being pretty lucky.
Amulets are traded because they have a value, not because they are "lucky"; being lucky isn't an objective trait, it's purely subjective.