Maybe its just me, but I don't see any reason why people need 10-15 mags for each gun they own. I'm not saying it should be regulated, just that I can't see how you could use them all. They're metal so they aren't breaking every few months, and you can only put one in the gun at once. I just don't see why you need more than 1-2 (assuming you don't lose or break things often) unless you do IDPA or can't stand reloading a mag right after you empty it. Could someone explain why 10+ mags are "needed" for each gun you own?
Need has nothing to do with it. WANT is all that is required.
All mags are NOT metal, many are plastic these days.
Many mags do break or lips get damaged (gouges on plastic lips or bent lips if metal).
No target or carry gun is adequate w/o at least 3 mags. When we did Appleseed, they stated 4 MINIMUM, 5 ideal!
Mags are a failure point in guns. If you need the gun to function, you NEED spare mags. I've had 6 mag failures of Walther P99 .40 mags due to a "bad batch of plastic" used in some baseplates. It happened on the range, and even some of the replacement bases that S&W shipped me failed . . . but what if it happened when I needed it to save a life?
Reloading while taking a course is a PITA, so having 10 loaded 1911 mags ready to go really saves on time/thumbs.
Sometimes we get a deal based on quantity.
Because of threats to ban mags and hopes that pre-ban (for the next ban) will be allowed.
Because idiot AGs threaten dealers who sell to MA so buying "when I need it" is very difficult, thus if traveling or you see a deal, you snap it up.
This is very much like "why do women have more than 1 pair of shoes?" or "why do men own more than two pairs of pants?" Because we can!