ambitious: describes someone who is willing to take initiative to tackle seemingly large projects in order to benefit lots of parties; having or showing a large desire to succeed
At the start of his career, Bill Gates was nothing more than a geek with access to very rudimentary programming facilities. Noticing his opportunity, he was able to transform this into an entire career, entering an industry everyone was sceptical of, in the end evolving and impacting it in such a way no one could have foreseen, and to such an extent that the world would be wildly different without his contributions. With Bill Gates at its forefront, Microsoft lead the way to revolutionize the industry time and time again.
On a less selfish note, Gates and his wife also founded the Bill & Melinda Gates Foundation, which has since contributed immense amounts of money to achieve many charitable goals. They put their huge net worth towards solving the world's problems in a way not many are capable of, and worse that not many are willing to do. Bill Gates sets an international example of how to shoot for the stars, and more importantly, how to make it.