Well first off, some couples shoot together, so purchasing two at once wouldn't be out of the realm of likely scenarios... but then of course there is this:
Personally I prefer accuracy to volume. .50 cal rifle is fun as heck to shoot(but at $5 a round, it's not cheap... yes, I said $5 PER ROUND... I need a new supplier...). BUT I'm not one to judge. I guess they think, "There's a bullet with your name on it. I'm not sure which one it is, so I'll just fire all of them." I don't see a problem with reporting large volume purchases. Or in the case of rifles, more than 3(mom, dad, little Timmy) should be reported to the ATF.