There are many ambitious people in the world — I am going to attempt to categorize them here.
90% of ambitious people are just striving to be popular. They are trying to accumulate better toys then their peers to enhance their popularity — just like 5th grade. You have the fast car, the cool beach house, the hottest pair of jeans — then you are more likely to be popular.
This sounds crude but my guess is that the 90% figure is not far off. Most ambitious people unfortunately are only ambitious because they strive to be in the "in crowd"
Plan verses chaos
Most ambitious people are planners. They have goal (like Bill Clinton: "I want to be President by age 50") and they work backward from that goal. Not all ambitious people reach their goal (as America has only had 43 presidents) but they use the goal as a guideline for advancement and promotion (and often they change their goal with more information).
A small minority of ambitious people live life without a goal. They generally never look more then 6-9 months ahead and only have some broad life objectives (like to make the world a better place). They have a much more chaotic path but are often just as successful as those people with a goal.
Means verses ends
There are ethically ambitious people and people who feel the ends justify the means. Some people who live by an ethical code are ambitious precisely because they want to prove that one can be successful and still follow strict ethical guidelines. Some people see more ethical grey.