One of the more important skills in this craft is the combination of intuition and knowledge to know when you don't know something well enough to achieve the goal. The difference between "ambition" and "hubris" is small but critical.
Then you shouldn't be working on it. If you can't be humble, you should not be working on things that can hurt people because you're creating risk for them that they can't actually measure. (It's why I consciously avoid such projects; knowing one's propensity to arrogance makes it unethical not to.)
If it's important, you need to be good. If it's very important, you need to be good and sure.
