[2] He was a Commerce and Law student of the University of Tasmania, studying tax, finance and banking, when he began card counting in Blackjack at the Wrest Point Casino.
[3] He subsequently relocated to New South Wales where he transferred his studies to the University of NSW in Sydney from which he eventually dropped out of to concentrate fully on advantage gambling.
[4] In 1994, Ranogajec reportedly won a $7.5 million Keno jackpot at the leisure and entertainment complex North Ryde RSL Club, of New South Wales, after reportedly[7] betting "significantly more than $7.5 million" to win it but coming out ahead due to the additional, smaller prizes awarded along the way to winning the jackpot.
In 2011 it was reported that the commercial failure of Tote Tasmania was partly due to the large rebates that Ranogajec had received on his betting turnover.
In 2012 Ranogajec was named as being the leader of a gambling syndicate which had profited from a rebate arrangement with Tote Tasmania Pty Ltd which was a Tasmanian state-owned company.
His business partner David Walsh believes that he does not owe them money as gambling on horse racing has never been a taxable source of income in Australia.
[10] After months of debt claims by the ATO, a settlement was agreed with Zeljko and other members of the punter's club, late October 2012.
[3] According to some reports, there could be some intentional confusion as to his real name, whereby he'd be using his wife's surname, registering as John Wilson for investment or gambling endeavours.
[25] Ranogajec has denied suggestions that he is the world's biggest punter, replying that "I believe that's absolutely untrue" and the magnitude of his betting and wealth is "all just a big exaggeration".