When I was eight my parents got a Mac 512K-E. It had one half of a megabyte of RAM and no hard drive. The floppy discs it used could hold as much as 800 kilobytes, or, 0.8 megabytes.
In the early 1990s we got a Mac LCII with an 80 megabyte hard drive and one floppy drive. I thought we would never fill up that hard drive. We did. At one point, over one quarter of the hard drive was taken up by the installation of King's Quest VI, the installation of which was contained on nine floppy discs.
My brother Andy purchased a one gigabyte hard drive a few years later. He allowed me to use 100 megabytes of it, which I thought I would never fill up.
We later got an iMac with, if I remember correctly, a four gigabyte hard drive. I thought we would never fill it up.
Shortly thereafter my brother Phil purchased what I considered to be the pinnacle of MP3 players at the time: an Iomega HipZip. It used removable 64-megabyte discs--more than enough for listening to music on the go.
My brother Phil also purchased one of the first consumer-level digital cameras in the early 2000s. He spent nearly one hundred dollars on a 64-megabyte card for it. I thought he was out of his mind to want so much storage space.
In the summer of 2004 I purchased an iMac with a ten-gigabyte hard drive. I was fairly certain I would fill it up.
In the fall of 2003 I purchased an external 160-gigabyte hard drive. I thought I would never fill it up. I began booting solely from the external drive.
In the spring of 2004 my iMac began smoking and stopped working altogether (perhaps a computer designed without an internal fan was a poor idea, Mr. Ive). I purchased an eMac with a 40-gigabyte hard drive. I continued to boot from the external 160-gig drive, thus ensuring minimal data loss in the event of another smoke incident.
In the summer of 2006 I purchased an external 250-gigabyte hard drive, bring my total storage up to near half a terabyte*. I thought I would never fill it up.
Today my wife and I purchased a 320-gigabyte hard drive for less than what Phil paid for his 64-megabyte camera card six years ago. I imagine we will fill it up, probably much sooner than we think.
*to put things in perspective, my brother Andy once told me that an isolinear chip holds roughly two to four terabytes