Amazon chief Jeff Bezos is launching a $2bn fund to help homeless families and build a network of preschools, saying the “child will be the customer” in his philanthropy announcement.

The tech founder and the world’s richest man unveiled the Bezos Day One Fund on Thursday. He said he would fund existing organizations that aid homeless people and pledged to build new not-for-profit schools to serve low-income communities.

“We’ll use the same set of principles that have driven Amazon. Most important among those will be genuine, intense customer obsession,” he wrote on Twitter. “The child will be the customer.”

Bezos, whose fortune has risen $64.7bn in the last year, has long faced scrutiny for his lack of a major philanthropic initiative and last year tweeted a broad “request for ideas” for a “philanthropy strategy”.

Bezos’s estimated net worth is more than $163bn, and Amazon recently became the world’s second company to be valued at $1tn – but Bezos has faced increasing pressure to improve working conditions and wages at his warehouses.

Earlier this year, Amazon was accused of treating warehouse staff like robots in the UK, after reports surfaced revealing that ambulances had been called 600 times in the past three years. There were also recent allegations of an increase in health and safety complaints from exhausted workers on Prime Day, when the company promotes a wide range of deals.

Some critics have argued that Amazon has become the world’s largest online retailer through opaque tax arrangements, and that the company should not be getting valuable tax breaks and should be subject to corporate wealth taxes. Amazon vigorously fought a tax to fund affordable housing in Seattle where it’s headquartered.

Bezos, who also owns the Washington Post, faced renewed calls for him to improve his labor practices and increase his philanthropy after he told an interviewer: “The only way that I can see to deploy this much financial resource is by converting my Amazon winnings into space travel. That is basically it.”

Bezos owns an aerospace company called Blue Origin.

Bernie Sanders has escalated criticisms of Bezos and his labor practices in recent weeks, tweeting: “Count to ten. In those ten seconds, Jeff Bezos, the owner and founder of Amazon, just made more money than the median employee of Amazon makes in an entire year.”

Sanders and California congressman Ro Khanna, a progressive Democrat, recently proposed the Stop Bad Employers by Zeroing Out Subsidies (Stop Bezos) Act, which would establish a 100% tax on large corporations that would be equal to the amount of federal benefits received by their low-wage workers. That means if an Amazon worker received $2,000 in food stamps, the company would be taxed $2,000 to cover the cost, according to Sanders’ office, which said the bill was designed to incentivize profitable corporations to pay living wages.

Khanna praised Bezos’s “entrepreneurship and commitment to philanthropy” in a statement to the Guardian on Thursday.

But Khanna said: “The biggest statement Mr Bezos could make is by raising the pay of workers in his own company. Philanthropy will not solve income inequality or stagnant wages. Raising wages like Henry Ford did in 1914 would make a dent.”

Bezos, who is worth nearly as much as Bill Gates and Warren Buffett combined, said his “families fund” would issue annual leadership awards to civic groups doing “compassionate, needle-moving work to provide shelter and hunger support to address the immediate needs of young families”.

His “academies fund” would “launch and operate a network of high-quality, full-scholarship” schools in underserved areas, saying he would “build an organization to directly operate” the preschools.

Tech billionaires’ efforts to improve education in America have had varying success. After Facebook chief executive Mark Zuckerberg pledged $100m dollars to schools in New Jersey, some local leaders said it was ultimately a failed effort. Research also found mixed results.