Because there are those of us who look at a box o' bullets setting on the bench and ponder 'what if?' That box of bullets stays with you, causing sleepless nights, gut churning, and an overall poor disposition... until their potential is finally realized, and you mash them into cases. Like the struggle between Good and Evil... that box of bullets is fine setting there on the shelf, but you are tired of looking at it setting there on the shelf... so you load it up, even though you don't need it. Then you have 100 cartridges loaded up... setting there on the shelf. You don't really want to waste them on paper, but you're tired of them just setting on the shelf, using up perfectly good brass. The Struggle goes on...
I've heard there is a Reloaders Boot Camp and Recovery Program out there, to break you of such madness. Next thing you know, I'll be turning necks and weighing brass...