Here are a few,
1- The smart guys are not able to dumb it down to keep things simple, I see this a lot from the Smart IT guys, they are very smart, they think in a complicated manner and come up with complicated logic and complicated steps, but they are not able to simplify steps and/or simplify design and functionality so a common man or operations guys can execute with much ease. Because of this many innovations fail - here is a good link on the number of innovation failures - Digging in to Why Supply Chain IT Projects Fail . The operations guys want to just go, go, go, they need to be able to do whatever they are doing as fast as possible by executing a couple of simple steps. But that requires a different way of thinking, which the IT smart guys don't always have.
2- The smart guys also don't have their head on their shoulders, just because they are smart they lose the humility and act weird, which pisses of many people and costs them opportunities
3- It is difficult for the smart guys to teach other people that are below their levels, that frustrates the person that wants to learn
Also check out my book Puga Sankara's Supply Chain Blog - that is a must read before spending Hundreds & Thousands of $$$ on your MBA or Masters Degree to get the best ROI or before starting your Entrepreneurial journey.