Ionizing radiation, metal whiskers, or the process of nucleation between others have something in common, they cause LED failures. High currents and mechanical stress are two causes that usually lead to issues in the world of electronics and with LEDs there's no exception.
In the packaging, temperature causes expansion and with it potential stress in the semiconductors. Stopping the degradation of materials continues as a challenge, and right now the expected lifetime of the LEDs stays published at 50.000 or 100.000 hours. For reference 100.000 hours is 11.4 years. Sadly, this could be wrong for too many reasons.
Even in the LED works properly, the control circuit is prone to failures. LEDs require DC current and today the standard comes in AC from power generators due to the nature of induction with magnets and their two poles. That means the necessity of conversion, protection and stabilization circuits. Common microcontrollers need external pieces as well to work and also DC current, so then more circuits. With DC to DC, there's the possibility of using switch mode power supplies that bundle multiple parts and charge a lot of stress in the bypass capacitors and semiconductors for switching.
Transformers, semiconductors, capacitors, inductors, resistors, soldering joints and finally every part fail. Perhaps it's not very realistic to guarantee a LED unit for 10 years and it's not very common. But some manufacturers do guarantee their units for a long time and take responsibility of the failures which is nice to select one or another brand.