You kidding??? That's called a very rational business model. I don't pretend to know the laws in France but I'm going to assume you folks don't have anywhere near the firearms freedoms we do stateside and therefore aren't very familiar with the gun market, but standard-capacity rifle magazines (incorrectly called "high capacity assault rifle magazines" by dickless gun banners) are a massive commodity in changing political climates.
Not to go into too much detail, but an example...back in 1993 you could buy basic 25-round magazines for a simple .22 rifle for about $12 at any WalMart. In 1994 the Clinton "Assault Weapon Ban" went into effect, banning sales of these mags but also with a grandfather clause. By 1998, those fuckers were going for up to $150/each private sale. I sold almost all of mine. In 2004 the AWB expired and those mags are now back to about $20.
In 2008, when Barack Obama started rising in polls, I started purchasing AR-15 magazines, milspec and aftermarket, for around $15-$25 each. I spent a couple grand on multiple cases, and after Obama was inaugurated there was unprecedented frenzy buying and massive shortages of all gun parts, especially magazines. Now those same mags were going for $50 up to $80 or even $100 each. I sold a case, made most of my money back and I still have enough 30-round mags for the next zombie apocalypse four times over.
Joe Biden has promised to make that idiot fucking douchebag Beto O'Rourke his "gun czar" if elected. Beto is promising to ban just about anything and everything he can think of (but not spell correctly). That means if Joe Biden wins, just one of the cases of mags I bought is going to fund my Rolex GMT-II Batman or a really, really happy adventure in Bangkok.
It's just like any savvy stock market investor, making money in good times and bad. I just know guns a lot better than Wall Street.