Forbes released its list of the world's billionaires with Bill Gates remaining the world's richest man, worth US$86 billion (NZ$122 billion).
While Trump's fortune is estimated to be down, Forbes said the average billionaire's fortune has grown by 16 per cent since the publication of the last edition of the rich list. He was followed by Berkshire Hathaway chief executive Warren Buffett, whose wealth was cited to be around $75.6bn.
Meanwhile, property mogul turned president Donald Trump took a dive in the ranking, slipping 220 spots to number 544 with an estimated $3.5 billion-$1 billion down from previous year. Dean White, who made his fortune in billboards and hotels, died previous year.
The biggest gainer on the 2017 list is Amazon's CEO Jeff Bezos (No. 3), whose fortune increased by $27.6 billion for a total net worth of $72.8 billion.
The global population of billionaires jumped 13 percent from last year to a record 2,043, the biggest annual increase in the 31 years since the magazine began compiling the list, Forbes said. White ranked 722nd on the year-ago list, with a fortune of $2.4 billion.
Other billionaires on the list include Mexican tycoon Carlos Slim Helu ($54.5 billion), Oracle co-founder Larry Ellison ($52.2 billion), brothers Charles and David Koch ($48.3 billion each) and former New York City Mayor Michael Bloomberg ($47.5 billion).
In his presidential campaign, Trump acclaimed that he was worth 8.7 billion dollars, then "in excess" of 10 billion dollars in a personal financial disclosure form. The English edition of his autobiography, Making it Big, was published a year ago.
Gayle Cook had previously made regular appearances on Forbes' lists until she transferred her wealth to her son.
The U.S. had the most billionaires with a number of 565, and China came the second with 319 billionaires.
Who made it into the billionaires club?
The top 20 billionaires have a combined net worth of $938.4 billion, up from $826.5 billion in 2016.
This year saw 15 new self-made women join the list, 14 from Asia pacific and one woman, Thai Lee, who was born in Thailand, but moved to the United States as a child.