I was a casual gun owner and occasional shooter up until the time I got my first job at a gun store some seven years later, about the time the Brady Bill became law. When the Violent Crime Control and Law Enforcement Act of 1994 (better known as the "Assault Weapons Ban") passed, I picked up a couple of extra magazines for my Glock 23 and SIG P-228, the only firearms I owned that would be affected. Conversely, I remember ordering a whole case of Ram-Line 10/22 mags for a customer who had a Ruger with an auto-sear in it. I thought he was being paranoid.
Boy, was I un-psychic...
Since then, my interests and preferences have shifted. These days my primary handgun doesn't hold over ten rounds, and the only weapons I own that do are various AR-platform carbines. But every time I go to a gun show, I buy at least one 1911 or AR mag. Any time I'm in a gun store and see that they have cheap ex-GI M16 magazines in their "Used Stuff" box, I pick one up. I keep replacement magazine springs and followers in my spare parts box. When I made my order from Brownells earlier in the week, I made a point of having them toss a carbine mag and a pistol mag in the box. Sure, maybe I seem as kooky as your great-grandparents who lived through the Great Depression and hoarded rubber bands and string until the day they died, but what's a little cheap insurance?
Magazines in self-loading firearms are wear items.
Q: How many mags should you have?