A few months ago I grabbed this torrent from rarbg, and it took weeks to download. Often going days with no seeders.
I finally got it, and decided I'd seed beyond my usual 2x to help others get this. Then rarbg went under, and now I think I'll just keep this one going.
And this is why I backup all the torrents I download. If I lose the drive, they might not be seeded anymore and I won't be able to re-download everything. There's stuff in my collection that was hard to find 5 years ago.
The only sane way to have a backup would be a NAS with raid 1. Other than that? Yeah, just drop them in a folder.
The other dude probably just has them on an external drive, if that fails they are gone.