I am exactly the opposite, and hate the learning curve part. I feel like I've just finally settled in after over two years at my current job. My husband is more like you, though. One thing he's done in the past is to switch teams, or departments, or things like that on a regular basis, so that he's working with different people and on different things but not actually switching companies. Another idea is to see if there are continuing education or extra trainings or things like that you can take on, so that you still have that 'newness' feeling. Or keep getting promoted, but in my experience that makes the dysfunctional bits even more your problem!
For myself, I take a lot of pride in becoming an expert in something, which does take time. The satisfaction I get from knowing exactly how to do my work best outweighs the dissatisfaction of the environment not being perfect. And my field (healthcare) changes so much on a regular basis that everyone's always on somewhat of a learning curve, so that probably helps too.