Concerns have been raised at how betting companies are targeting children with ads, with one activist going so far as to brand it "grooming".
The Alliance for Gambling Reform estimates more than 430,000 people under the age of 16 are likely betting online.
Reverend Tim Costello said the lack of federal regulation on gambling advertising meant operators were able to "groom our kids with impunity".
"And the implications will be horrific and lifelong."
Rev. Costello told parliamentarians reviewing gambling reform that betting companies had built a myth around mateship, such as through the plethora of betting with mates ads.
He said when he first started researching the sector, he came in with the idea that Australians just loved to punt, which is what led to such great gambling losses.
But he's now changed his mind, saying the losses don't come from a culture "that loves it more than anyone else", but from a lack of regulation.
"The truth is, we've had the worst policies, the least regulation of gambling," he told the reform inquiry on Monday.
"That is why we have the greatest losses."
While there is limited oversight of gambling advertising by the Australian Communications and Media Authority, Rev. Costello branded the watchdog a "toothless tiger".
Gambling giants Sportsbet and Ladbrokes have defended their huge advertising presence but admitting targeting minors with ads is out of line.
Sportsbet used its submission to the inquiry to acknowledge more solutions were needed to protect minors and people at risk of harm but said any protections had to be balanced against a company's legal right to advertise.
The reform alliance also lambasted the government for not taking gambling as a serious public health issue.
CEO Carol Bennett says in her 30 years of working in the public health system, she's seen Commonwealth and state and territory governments come together to tackle a range of health issues.
This includes prevention, early intervention, research and awareness campaigns.
Except for gambling.
"This is an anomaly in this area, that doesn't occur," she said.
"You don't have a response that looks at the public and its need for protection from a harmful product."
Ms Bennett said including the gambling industry at the table to talk about harm reduction would hinder an adequate public health response.
"The gambling industry makes money by making losers, that's the reality," she said.
"Reducing harms ... is at odds with their purpose."
