When being ambitious not only isn't wrong but is desirable.
But not the regular 'ambition' which has negative meanings related to money, power.... It's more of an intellectual and personal meaning. Being surrounded by big people, hard-working, intelligent, sensitive, motivated, you work harder. You try to get to their level, it's as simple as healthy competitiveness. Then when you are not lucky enough and aren't surrounded by that atmosphere, motivation has to really come from inside, from your own ambition, your own dreams. Then dream big. There's nothing I dislike more than people with weak minds, conformist, tired to have interest, not so tired to be resolute about the things they dislike but mundane enough to accept the topic 'things can't be changed'. People who have access to way more tools than they will ever try to use, people determined to follow an intellectual path as long as it's been already traced by somebody. People for whom it's easier not to doubt because finding the answer to a 'why' isn't really worth the time it takes.
Have ambition, dream about being never tired of learning, daydream about problems that are not solved, find other viewpoints, strongly force yourself to think hard enough to end the day with questions to ask or questions answered. Accept the facilities of an established path; refuse it to be the main and only. Don't fear confusion, fear the easy given certainty.