The Rising Sun Hotel in Richmond, Melbourne, is hardly the place you’d expect to run into a couple of soon-to-be billionaires. But Sam Hupert and Anthony Hall, founders of ASX-listed medical imaging firm Pro Medicus – worth about $2.5 billion – happen to have an office across the road.

The glimpse of a not-quite-new silver Porsche in the car park behind their modest headquarters of 25 years is about the only sign that Hall was last year catapulted onto the Financial Review Rich List (Hupert just missed the cut-off), with each worth between $500 million and $1 billion.