1) No one expects security in these places to be Hollywood grade lasers, knockout gas, explosive bolts shuttering down inch thick steel plates in an instant. But 7.5 minutes seems a tad long to have gone, per lack of reporting on anything at all about security guards, without being either opposed or confronted, or otherwise encountering obstacles to escape? (I've seen a story also say 4 minutes. The specific timeline might have been revised? Either that or they're deriving their metrics from different start/end points on what constituted beginning and ending the of the theft.
2) Also, this: “One of the jewelry items was found near the Louvre”. Careless that, someone isn't getting a bonus, but I'm not sure if that points either to ineptitude of non-professionals taking a rare opportunity, or professionals who simply had an unlucky fumble but were smart enough not to double back for it.
3) Finally: The market for these is, what, maybe 100 people in the world? That have the desire for this sort of loot, as-is? Because chopping them up and selling piecemeal is not an economically viable risk/reward calculation. Their value is their cohesion, at least as individual pieces and especially as a set. Otherwise, old jewels certainly have a lot of value but they're also not so rare in their individual pieces as to require this high profile of a burglary. So, specific buyers in mind and a commissioned theft I would think? Then again there have been some "dumb thieves" high profile thefts in the past so its not impossible. And it's not so nice a thought to think we're at the point in this world where billionaires are dispatching gangs of thieves in the old Hollywood tradition, instead of keeping their thefts of the more traditional