There's a poster in my living room that reads:

"Ambition

The world makes way for those who know where they are going"

Usually when people talk about ambition they refer to it as something bad, like someone driven/blinded by his ambitions can do something really bad to others. But I'm gonna have to disagree.
Ambition is what drives people to evolve. It's what motivates them to follow their dreams.
Ok, so some people driven by their ambitions, sometimes, tend to step on other peoples bodies, but nothing was conquered without any victims! And even though not many people admit it, we live in a world where the big fish eats the small. We strive to survive and make our dreams come true.
Oh, by the way dreams are ambitions! You can't say you're not ambitious if you have a dream or a desire. People without ambitions are like empty shells!
When I talk to others about stuff like that they always say that not all people are like that, not everyone is willing to sucrifice others people dreams in order to meke their own come true. I have to admit, if I had a chance to make my ambitions come true but had to stain my hads with "blood" in the way, I would only care if it was someone's I care about.
People don't realise how many things they are willing to do in order to make themselves happy until the day comes when a chance finally shows up!