Forbes pinned his wealth shrinkage on the receding real estate market.
While the global economy might not be rosy, it was still a record year for the richest people on earth, as the number of billionaires jumped 13% to 2,043 from 1,810 last year, the latest Forbes report states.
There are 183 tech billionaires in all with a combined $1 trillion in wealth, Forbes said.
According to the magazine's annual rich list, Mr Gates' fortune rose to $86bn, from $75bn, followed by investor Warren Buffett, up $14.8bn to $75.6bn.
In an article published in September 2015, Forbes wrote that no other mogul featured on their annual rich list has been "more fixated with his or her net worth estimate on a year-in, year-out basis than Donald J Trump".
Meanwhile Microsoft founder Bill Gates kept his top spot on the Forbes list, with a fortune of US$86bil (up from US$75bil in 2016) for the fourth year running.More news: South African opposition parties aim at President Jacob Zuma
Others in the top ten, which is heavily dominated by Americans in the technology sector, were Facebook founder Mark Zuckerberg, at number five, Oracle co-founder Larry Ellison at number seven and Amazon's founder Jeff Bezos. (No. 564, $3.4 billion), Tony Tan Caktiong (No. 564, $3.4 billion), David Consunji (No. 630, $3.1 billion), Andrew Tan (No. 814, $2.5 billion), Robert Coyiuto Jr. China comes next with 319, while Germany is at number three with 114.
Mobile wallet Paytm founder Vijay Shekhar Sharma is ranked 1,567 with his net worth of $1.3 billion and is "one of the biggest beneficiaries of the government's decision to demonetise 86 per cent of India's rupees and move to a cashless economy", Forbes said. "Lately, the neighbourhood has been struggling".
A recent breakdown of the president's wealth valued his New York City real estate at $1.7 billion, his real estate outside New York at $630 million, his golf clubs at $620 million, his cash and personal assets at $270 million, and his brand businesses at $230 million.
The magazine likewise said that his riches was hit by $66m in political spending on his successful presidential campaign, together with $25m to settle litigation pupils were supposedly ripped off by him at Trump University.
Overall, there were 227 women billionaires, the majority of whom inherited their wealth.
Rounding out the Forbes top 10, Amancio Ortega of Spanish apparel chain Zara was fourth; Mexican telecom tycoon Carlos Slim was sixth; the Koch brothers, USA conservative political activists Charles and David, were eighth and ninth; and former New York City mayor and Bloomberg News founder Michael Bloomberg was 10th. But the list also contained 15 new "self-made" women, mostly from Asian countries, including Vietnam's Nguyen Thi Phuong Thao of budget airline VietJet air.