Why is the alternator bad after 2 years?

Hello, 2 years is a little short, but I would certainly not consider it abnormal. If there is a high load on the alternator, such as a sound system, large lights, or other equipment, or if the alternator is inferior in quality, the shortened time-span could be explained. Ensure the grounding cables for the battery and engine are clean, tight, and serviceable, and make sure the replacement part is OEM quality or better.