Laura Ingalls Wilder wrote the following as her first essay when she was still a schoolgirl, and shared it in the book These Happy Golden Years. I think she had an excellent grasp of the good and bad of ambition, especially at such a young age!

“Ambition is necessary to accomplishment. Without an ambition to gain an end, nothing would be done. Without an ambition to excel others and to surpass one’s self there would be no superior merit. To win anything, we must have the ambition to do so.
Ambition is a good servant but a bad master. So long as we control our ambition, it is good, but if there is danger of our being ruled by it, then I would say in the words of Shakespeare, ‘Cromwell, I charge thee, fling away ambition. By that sin fell the angels.'”