Hains graduated from the University of Melbourne. He started his career as an Engineer and corporate restructurer. Through his Portland House Group, he invests in equities, fixed interest, property and managed funds globally. It is Australia's biggest hedge fund. He runs it with his children. In 1993, he sold an investment to Wheeling-Pittsburgh Steel for US$107 million.
According to the BRW Rich 200, Hains' net worth was estimated as US$2.48 billion in May 2016; and by Forbes Asia his net worth was estimated as US$1.90 billion in January 2016.