"We see women being killed by gender-based violence so regularly in Australia, and it's something we're struggling to take seriously," he told a women's health gathering.
"When that's spoken about, you get this mass pushback from men saying 'well it's not all men', but it is men."
Many young males don't have good role models and "manosphere" social media influencers were exploiting this gap for profits, the former player-turned-activist said on Tuesday.
He said Australia needed to push back by creating a different version of what being a male was about, for young boys to aspire to.
In 2025, Foster joined a NSW multi-sport coalition bringing sporting organisations and clubs together to address domestic, family and sexual violence.
"I had great hope. I thought that the new generation ... they've come through in the most diverse Australian society that we've ever had. That's starting to be broken down now," he said.
"How do Australian men come together to say that we want to push against this and we want to provide a different vision of what an Australian male is about?
"If every women's organisation in Australia was united here with men's organisations and prominent males in the country, I'm pretty sure it would be very difficult to stop."
Monash University professor Steven Roberts, an expert in masculinity who has researched the "manosphere", joined Foster on the Women's Health and Wellbeing Summit in Sydney men's panel.
"We have to recognise that misogyny is baked into the Australian culture, and it's being reanimated in this moment," he said.
The building blocks of masculinity for boys began early, from what toys they played with to how they dressed, Prof Roberts said.
"Those commitments to rigid, narrow versions of what a boy can be is the building block for the violence that we're we're talking about now," he said.
Prof Roberts said engaging in youth culture online, like dating, fitness and football, was being used as a gateway to anti-feminist and anti-egalitarian content.
Boys would then fall into three categories: being exposed to misogynistic content, engaging with the content or accepting its views, he said.
"They're met with this content that teaches them how to hate women, and that it is necessary to hate women to find your place in the world," he said.
Prof Roberts said the antidote was normalising role models "in all genders".
The problem was seeping into classrooms, with Prof Robert's recent research showing 78 per cent of teachers have observed or experienced sexism or misogyny at school.
"It takes good role models, male role models, but it also takes normalising role models in all genders," he said.
"Consolidating the myth that boys need male roles models plays into the hands of the manosphere.
"We need legislation as well, we need government, policymakers, and legislators to be brave and hold the social media companies to account."
AAP's journalist attended the Women's Health and Wellbeing Summit with travel assistance from Women's Agenda.
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