Not sure this holds either. With such a black swan event, there would be a glut of second hand graphics cards on ebay etc.
Seems safer to me (if you're worried about a huge crash) to leave your principle investment equivalent amount on a good exchange with fiat support (e.g. Bitstamp) setup a sensible stop loss order and then, as soon as you've x2 your original investment, pull your initial stake out and leave the rest in crypto (on a Nano Ledger S or similar).
I think people are going to be increasingly wary of second hand graphics cards. How many of them will have been trashed by running in a poorly-cooled mining rig for months on end?
Seems safer to me (if you're worried about a huge crash) to leave your principle investment equivalent amount on a good exchange with fiat support (e.g. Bitstamp) setup a sensible stop loss order and then, as soon as you've x2 your original investment, pull your initial stake out and leave the rest in crypto (on a Nano Ledger S or similar).