I assume he's referring to carrying it on, where you can maintain physical proximity to it, rather than checking it.

I'm pretty skeptical that you can take a package containing 100 SNES games as carry-on.

There's no way that happens, especially if they're boxed. The boxes are something like 180mm * 105mm * 30mm or 567000mm^3, a carry-on is 220mm * 350mm * 560mm or 43120000mm^3, if you just tape up and wrap all the boxes into a carry-on-sized package you're barely fitting 76 boxes volume-wise, and I'm not sure you can actually lay them out such that they'd fit in the prescribed dimensions.

In photography circles in the US it is occasionally suggested put a gun (can be a flare gun) in the luggage as well -> it then has to be specially tracked and is supposedly looked after a lot better. No clue how much truth there is to that.

There certainly are additional declaration, inspection, and tracking requirements for firearms in checked luggage, so it might well be a cheap way to get extra insurance that your expensive camera gear ends up in the same place you do.

>And how often do airlines lose luggage? More often than packages go missing. 

Are you sure that's true? I think the loss rates of both are around 1%

But yeah as dtparr said, obviously don't check your luggage. If it's too big to carry on, take it to the gate instead of baggage drop to ensure that it's manually put on the plane.