5.25 inch floppy disks were fragile. They had to be stored in paper sleeves, could not be bent, and they could be damaged by a single touch
3.5 inch floppy disks held 1.44 megabytes of data. That's enough for maybe two or three standard Microsoft Word documents with no images. That's enough for maybe a minute of MP3 quality music.
Before internet use was common, the most frequent way that computer viruses spread was through floppy disks. It was a risk to take your data to another person's computer.