They undervalue social skills
Some intelligent people don’t realize that intellect is only one element of achieving success and that personal connections are powerful in the professional world. They never try to improve their social skills, learn to network, or self-promote, and often denigrate people who excel in these areas.
They are too independent
Smart people can fail to develop healthy support systems that everyone needs to succeed. Without a good support system, anyone can begin to slide down a slippery slope when they encounter hardship, miscalculate something major, or fall victim to the misdeeds of others.
Teamwork can be frustrating for very smart people.
When someone grasps concepts quickly and has high standards for their own performance it can create difficulties when working with others who take longer to process information and pick up concepts.
Again, smart people also sometimes find it difficult to delegate because of a sense they can do a task better regardless of whether this is actually true.
They become risk-averse
Very intelligent people tend to be high achievers that end up in the company of those who are similarly smart and motivated. But that motivation can become confined to a small window for fear of embarrassment, resulting in “not opening up or trying something new which they know they aren’t naturally good at, because they fear loosing the ‘Smart’ tag in front of their peer group.