September 10, 2015 6:14 PM EDT

Bill Gates’ personal net worth — an estimated $80 billion — rivals the GDP of Ecuador and tops Croatia’s.

The Bill & Melinda Gates foundation, which he and his wife set up in 1997, gives away nearly $4 billion a year.

In 2013, The Financial Times wrote that “Gates probably now has the power to affect the lives and well-being of a larger number of his fellow humans than any other private individual in history.”

How did the world’s wealthiest man get to where he is today? Gathered from 20 years of interviews, these quotes show how Gates grew from startup nerd to software titan to history-shifting activist.

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