Moore's Law is only partly your friend here - storage keeps getting cheaper rapidly, but that also means that not only do devices become obsolete, but the interface specs and data formats also become obsolete. You probably don't have an 8" floppy drive anywhere, or a working 5.25", or the right kind of cable to plug the 5.25" drive into, or a Bernoulli drive, or a 9-track tape drive (800, 1600, or 6250dpi), or the Sun cartridge drive, or anything to plug those MFM drives into, or SCSI-1, or probably SCSI-2. You might have something that can handle IDE / PATA, or an old laptop with PCMCIA, but even those are getting scarcer. If you can connect to that old disk disk drive, you can probably load a virtual machine running NetBSD that'll have drivers for the file system format, but maybe not; you certainly don't want to risk having Windows "update" the format. You might think that FAT 8.3 format will stick around for a long time (and maybe it will for reading, but it's rapidly getting replaced with FAT16, FAT32, ExFAT, NTFS, etc.
Leave aside the question of whether you can read a 20-year-old version of WordStar or WordPerfect format file (unlike my late-70s nroff files, which would be readable if they weren't on a 9-track tape I've probably lost.) You can probably read that 4-year-old TurboTax file, but if you need to get tax data back from when you bought your house, you'd better have everything on paper.
Just for physical format alone, you need to copy stuff every couple of years.