True performance

There are four kinds of performers:

1. With a task that is bigger than their ego.
2. With an ego that is bigger than the task.
3. With a big ego matching a big task.
4. With a small ego matching a small task.

Type 4 is simple: weak competence and weak performance, which is made palatable by modest behavior and modest pay.
Type 2 is common: whatever the position, the performance is to advertise the person, to advance in power, money and career prospects. What task? Think Berlusconi. A lot of vanities and an often long wait for the bonfire.
Type 1 is rather common: when people really try to do a good job. At the very top it is less common: think Harry Truman.
Type 3 is overall less common: when a strong personality is needed for a heavy job. Think Churchill, possibly Kennedy.

In organizations with are cursed with type-2 leaders, type-1 people are forced out. Type-4 people remain, with a whole bunch of type-2 crowding in the higher layers.

A blog is an acceptable place to simplify. So here it goes: Technical people tend to be type 1, administrative people tend to be type-4. Commercial people tend to be type-3. If they are type-2, they will usually fail after a time. But some make it to the top.
Financial and legal types are both in the large-ego and small-ego types. The small-ego types fill the many staff functions, the large ego-types make it to the top. As they usually have neither technical nor commercial competence, they engage in massive, impressive change projects that will show their real effect after they have gone over to their new positions: mergers, acquistions, selling off parts of the organization, reorganizations, efficiency drives. It's mean people that make lean organizations. Before you know it, the last people that have practical knowledge of products and clients are banished from the board room.

Whatever the size of your ego, try to make it bigger. As long as your mission in life is commensurate with your sense of self. To look for true challenges is not enough. Your challenge should be meaningful as well.  How many dragons have you slain sofar?
Now be careful before positioning yourself as a knight on a white horse. Many a knight has entered the cave, slain his dragon and married the princess, only to discover afterward that the princess was the real dragon and that the dragon did humankind a favor by keeping her behind lock.
Without common sense and practical wisdom any ego may be too big, any task may be too big. Go for rewarding and meaningful performance. And retain a sprinkle of dissatisfaction always. Nobody is perfect. (Famous last words.)