"The noble Brutus told you Caesar was ambitious. If it were so, it were a grievous fault." – I always thought it interesting that Shakespeare clearly thinks ambition is a vice, and then something changed in the culture to make it a virtue.
"Get thee to a nunnery. Why wouldst thou be a breeder of sinners? I am
myself indifferent honest; but yet I could accuse me of such things
that it were better my mother had not borne me. I am very proud,
revengeful, ambitious, with more offences at my beck than I have
thoughts to put them in, imagination to give them shape, or time to act
them in."
I think ambition evolved out of the protestant workaholic ethic in which productivity was king, then in the 20th century it was that productivity meant ambition and ambition meant wealth (at least momentary wealth for the working class that would soon be taken from them again by the capitalists).