I don't think it will destroy the hard disk as such.
The hard disk is just a spinning thing that is in use nearly all the time in the background. There is always something being read from, or written to, the disk, so installing and uninstalling is no different.
But if you are "always" installing and uninstalling programs, then the data on the hard disk can become fragmented after time, and that makes seeking programs/files, or managing the disk, harder for the Operating System.
That is what the Disk Defragmenter is for. In Windows XP it is a particularly unfriendly looking piece of software, but if run regularly, (eg once a month if you install/uninstall very often, or less frequently otherwise), it does it's job pretty well.
The Disk Defragmenter can tell you what percentage the disk is fragmented, and will recommend that you either defragment now, or defragmenting is not required at this time.
Is it true that if we always install and uninstall programs most all the time, it can destroy the hard disk?
Thanks for the answers!!