The bulbs generally contain around 10 LEDs arranged in series, so if any one of them fails, the bulb no longer works. Also they are generally not cooled well, and the heat leads to faster failures.
If you have a dead one around, pry it open and you’ll likely see some slightly charred or discolored plastic and also one LED with a tiny charred spot.
Seems like it would be easy enough to mitigate both of those problems with basic design improvements, but cheap design causing early failure is sort of a win/win from the mfg perspective.
Pathetic, I have relatives with more guns than that. And I think most gun owners probably have more ammo than that.