He also bought the Seattle Seahawks and the Portland Trail Blazers, and became a minority owner in the Seattle Sounders. He purchased an 18.5 percent stake in DreamWorks and created an independent film-production company, and he opened the Allen Institute for Brain Sciences and the Allen Institute for Artificial Intelligence. He gave $100,000 this year to a group trying to keep Republicans in control of the House; he has also given to Democrats. His super-yacht had a pool, a movie theater, and 41 suites.

But the day he died, he was worth $20 billion—48 percent more than he was when he signed the pledge. It’s a sign of just how broken the American system of wealth is: A billionaire pledges to give away half his fortune and, despite donating generously and spending liberally, ends up with even more money than he had before. The same seems to be true for many of the people who signed the Giving Pledge. Bill and Melinda Gates gave away $141.4 million in 2016, according to The Chronicle of Philanthropy, but that was just 0.2 percent of their net worth of $81 billion at the time. (Their current net worth: $95.9 billion.)

Allen played by the rules: Make billions of dollars through honest, hard work, and then pledge to give away much of it. It’s a model made famous by Andrew Carnegie in his 1889 essay, “The Gospel of Wealth,” in which he argued that citizens would be willing to accept some of the problems caused by capitalism if philanthropists spent some of their earnings to solve some of those problems. But critics have recently started to question a system in which people can make so much money, and then, while giving away much of it, also use that money to reinforce the market-based system that helps perpetuate their wealth. The super-rich “are the beneficiaries of tax laws that give carried interest a major break and help to keep the public coffers low and the schools attended by the city’s poor underfunded,” Anand Giridharadas writes in his book Winners Take All: The Elite Charade of Changing the World. “But these men have been generous, and in exchange for their generosity, these issues will not come up.”

As Giridharadas points out in his book, the super-rich are increasingly doing better and better. The average pretax income of the top 0.001 percent of Americans has risen sevenfold since 1980, while the average pretax income of the bottom half of Americans has stayed the same. And the fortunes of the world’s billionaires grow at more than double the rate of everyone else’s.

It is surprisingly difficult to give away $10 billion. Most nonprofits wouldn’t know what to do with such a large gift, which would likely require growing staff and space exponentially, nearly overnight. The scrutiny around high-profile donations has also made philanthropists skittish: Mark Zuckerberg famously gave $100 million to the Newark, New Jersey, public-school system, only to be criticized for not consulting the local community. The Red Cross reportedly squandered the half a billion dollars it received in donations after the Haiti earthquake. “No one wants to be the one who made a big bet and lost,” Ray Madoff, a professor at Boston College Law School who studies philanthropy and tax policy, told me.