There's an inventory cost to keeping DVDs on hand, so for older content that doesn't sell well, it can be worth it to sell a DVD for less than you bought it for

There's an inventory cost to keeping DVDs on hand, so for older content that doesn't sell well, it can be worth it to sell a DVD for less than you bought it for wholesale, just to clear it out of your inventory. That's never going to be true of digital download.