The amount of storage space that we use on hard drives has clearly exploded. As we can see in the link below, we once used compact discs with 450 megabytes or so of space and thought that those media were large. Today, hard drives with terabytes of space are common. The main cause of this change has been the explosion in digital media and in our desire to store such media on our hard drives. This trend may be ending, however, if we start to move more towards cloud computing.
Years ago, there were no digital cameras, no digital music, and no digital video. This meant that the main things that went on our hard drives were documents and a few programs. This situation no longer exists. Now that we have digital cameras, people take tremendous numbers of pictures and store them on hard drives. People have huge libraries of digital music also stored on hard drives. They have files with movies and other video on their hard drives. This causes a demand for a huge amount of storage space.
This trend is likely to continue unless we start to move much of our storage from our own computers to the cloud.