Trump has also come a long way in terms of betting odds: He was first offered to bettors with "no-hope odds" of 200-to-1 to make it to the White House, according to the bookmaker. After last night's primary, his odds are 2-to-1, or 33 percent.
While betting on political contests is illegal in the U.S., it's permitted in the U.K. One of Trump's biggest bettors is a British investor who placed about $10,400 in bets and hopes to win $112,000 from William Hill. John Mappin, owner of the Camelot Castle Hotel in Cornwall, England, began betting on Trump in July when the candidate was 20-to-1 to become the Republican candidate.
Sharpe said he and many others underestimated Trump's appeal and commitment and could pay the price.
"Donald Trump was seen originally in being a useful figure to make people aware of the impending election before the serious contenders moved him aside and decided who would be Hillary's authentic challenger," Sharpe told ABC News.
According to Irish bookmaker Paddy Power, both Trump and Clinton’s odds have improved in the past month as they both increased their lead over their competition.
On the other hand, Sanders was 20-to-1 last month, and went to 40-to-1 after New York’s primary results on April 19, according to Paddy Power. But now the Democratic ticket hopeful has settled into 33-to-1 following his surprise win on Tuesday.