American technology executive Tim Cook is worth an estimated US$625 million.

As the head of Apple, he is the first openly gay CEO on the Fortune 500.

A day in the life of rich man Jeff Bezos, who always offers to do the washing-up

This year Apple became the first United States company to be worth US$1 trillion.

Yet compared with his counterparts in the technology world, his net worth is pretty modest.

Google founder and Alphabet CEO, Larry Page, is worth US$53 billion.

I like to be reminded of where I came from, and putting myself in modest surroundings helps me do that
Tim Cook, CEO, Apple

Facebook CEO Mark Zuckerberg is worth just under US$70 billion. And Amazon CEO Jeff Bezos is the first person in modern history to accumulate a fortune north of US$100 billion.

Apple’s best-paid exec earns nearly twice as much as CEO Tim Cook

Cook does not lead a lavish lifestyle and has said: “I like to be reminded of where I came from, and putting myself in modest surroundings helps me do that.”

The Alabama native had a humble start in life as the son of a shipyard worker and pharmacy employee.

When he became Apple’s CEO in 2011, his base salary was US$900,000, which had risen to US$3 million in 2017.

He also receives a cash incentive based on the company's performance, which pushed his total pay for 2017 to more than US$12 million.

How does Jeff Bezos, the richest person alive, spend his billions?

However, his net worth consists mainly of US$622 million worth of Apple's stock and options he has collected since becoming CEO – plus US$3.4 million of Nike stock options he gets as a member of Nike’s board of directors.

So, how does Apple’s leader spend his fortune?

Quite differently than other CEOs of technology giants.

Tim Cook reportedly buys his underwear at luxury department store Nordstrom’s semi-annual sale

In 2012, he bought a 2,400-square-foot (220-square-metre) home in Palo Alto, California, for US$1.9 million; the average cost of a home in Palo Alto in 2018 was US$3.3 million.

Yet his frugality doesn’t stop at the housing market.

He reportedly buys his underwear at luxury department store Nordstrom’s semi-annual sale.

How does Giorgio Armani spend his US$9 billion fortune?

However Cook does splurge when it comes to donating to good causes – a philosophy that differs from that of his predecessor, the late Steve Jobs, who lacked a record of public giving.

He encourages his staff to give and has led Apple into many philanthropic endeavours.

In 2011, he set up a company-wide, non-profit donation matching programme.

Over the past 10 years, Apple has contributed US$130 million to help the non-profit brand RED fight Aids, US$100 million to advance diversity in technology, through former US President Barack Obama’s Connected initiative and US$50 million to hospitals.

Cook practises what he preaches, too.

He has donated to civil rights efforts and this year donated more than 23,000 shares of his Apple stock, valued at just under US$5 million, to an undisclosed charity.

You want to be the pebble in the pond that creates the ripple for change
Tim Cook

He also regularly makes campaign donations. In the past he has hosted fundraisers for Obama and former US presidential candidate Hillary Clinton; in 2016 he donated US$236,000 to the Hillary Victory Fund.

How Elon Musk spends his US$20 billion fortune

Cook’s altruism even applies to his future financial plans.

He intends to use his wealth to put his nephew through university.

Upon his death, he plans to give away all his money to good causes.

He told Fortune magazine: “You want to be the pebble in the pond that creates the ripple for change.” 

Want more stories like this? Sign up here. Follow STYLE on Facebook, Instagram and Twitter

This article originally appeared on Business Insider.