The business tycoon, with $3.1 billion is now ranked 766th this year, down from a 544th ranking last year.
The estimate is well below Mr Trump's claim during the election campaign in 2015 that his net worth was "in excess of ten billion dollars".
Globally, Amazon CEO Jeff Bezos headed the "three-comma club", breaching the US$100-billion barrier - the first time anyone has crossed that milestone in the Forbes list. Americans lead the way with a record 585 billionaires, followed by mainland China with 373.
Villar, meanwhile, doubled his estimated net worth to $3 billion from last year's estimate of $1.5 billion.
The steep rise in Amazon's shares have made him America's only centi-billionaire by amassing over $100 billion in wealth.
Seventh set of remains linked to alleged Toronto serial killer Bruce McArthur
Toronto police have released this photo of a man they believe is a victim of Bruce McArthur in the hopes of identifying him. And on the accused serial killer's computers, photos of his suspected victims were discovered on the hard drive.
The Bezos milestone, revealed in Tuesday's release of Forbes' closely watched list, underscores the growing clout of both Bezos and the company that he founded in 1994 as an online bookstore.
Although the value of his assets have increased over the past year, Lakshmi Mittal slid to the 62nd rank on the 2018 global list and to the third spot among Indians with $18.5 billion from the 56th worldwide rank with $16.4 billion in 2017.
Helping move Pritzker up to fourth on the list of richest Illinoisans was the downfall of Rishi Shah, the health care technology entrepreneur who has been accused of misleading investors on sales figures. His fortunes rose by $39.2 billion over the past year, which Forbes said is the list's biggest one-year jump ever.
Both Gates, 62, and Buffett, 87, have committed to giving away most of their wealth while Bezos, 54, hasn't said much about his philanthropic plans.
Facebook founder Mark Zuckerberg comes in fifth, with an estimated fortune of $71bn. The 2,208 men and women are from 72 countries and territories, and, together, they're worth $9.1 trillion.