You must regularly back up your data. Most genealogy programs have a backup feature that compresses the files so that you can get much more on a disk. After a few years of doing genealogy, using floppy disks for backup will get very unwieldy since many floppy disks will be required. There are several web sites that provide free backup disk space. The price you pay is having advertizing display on your computer screen when you do the backups.
Every new computer has a CD-ROM drive.
Therefore, I can share my data with anyone with a new computer. Not every new computer has a ZIP drive. CD-ROMs in jewel cases are probably not any more susceptible than ZIP disks to mechanical damage. Such disks cannot be written more than once. These disks cannot be read by CD-ROM drives built before 1997.