I feel like the Holmes brothers (I'll include Q in this as well since it worked in Skyfall) suffer from reaching a bit too high sometimes due to arrogance. The fall can be painful. Mycroft can control a lot of things but sometimes countries will do what they want.

Yes! There is definitely too much self-confidence there, and it gets them into trouble. I also think there's a level of, because they are so smart and it's all academic, it can hit them hard when there's a human cost to their mistakes. They forgot it's real life they're playing in.