Why I save and backup installation media

Five years ago, I purchased a USB DVD burner/player. It came with a basic program for playing videos, which was fortunate, because that was right about when Microsoft discontinued the free Windows Media Player.  Just in case I lost the install disk I copied the DVD executable file (.exe) to a safe place so I could reinstall the DVD program whenever I changed computers. Unexpectedly, it was also much more convenient to install from the executable than searching for the disk each time.
Now, I also save executables from open source programs in case I need to reinstall them. In addition, I sometimes save the full media image as an .iso.  I collect them by type and store the images on external hard drives.
I will never know when the cyber apocalypse will come, but at least I am ready with all my programs.