Ambitious people are high maintenance because they have created that kind of life for themselves. This is also the same reason why they're down to earth; it's because they have faced all kinds of adversities while getting where they are.
6. They seldom ask for help.
Ambitious people believe in carving their own way and will hardly ask anybody for any help. It's not about their ego, it is more about doing things on their own and being self-made.