That's only part of the process (precomputing the large files you need to win). Once you have the files, they can be stored anywhere and that storage is only lightly used.

SSDs are destroyed but HDDs are not.

This wouldn't stop an unscrupulous seller from almost wearing out an SSD, then selling it on eBay to an unsuspecting buyer as a "working SSD" and buying a new one

it depends on the drives. CAN you destroy drives by plotting? yes. But other drives can take quite a beating - and generate 40K plots worth of data before reaching failure point.

additionally, farming (serving plots) is done with regular drives, and those are very lightly read from and used once the plots are loaded.