I remember when I upgraded my Macintosh SE (2 3.5” floppy drives) with a 30MB hard disk from Seagate. My friend said I was “crazy.” “You are NEVER going to fill it!”
My first PC hard drive was 40MB. Then I found out that by swapping out the MFM drive controller for RLL I could boost the capacity to 60MB. That was a lot of space back when the OS would fit on a few floppy disks.