The OP is mixing mediums with different characteristics. The DVD has a fixed size (say, 5.x GB), while hard disks are relatively open-ended. One can buy 10+ TB

The OP is mixing mediums with different characteristics. The DVD has a fixed size (say, 5.x GB), while hard disks are relatively open-ended. One can buy 10+ TB magnetic disks for a cheap price (less than 200$). If the OP really needs dozens of TBs of capacity every few year, they definitely don't fit in the home user market they are talking about.