I've argued this on HN plenty of times and I get drowned out by people telling me that they like bacon too much and that "well e-coli can spread on lettuce too so we might as well keep breeding hundreds of billions of animals per year and keeping them in filthy conditions in close proximity."

For a very scientific community, you absolutely hit a brick wall as soon as you tell a typically unhealthy group of people that eating meat is a massive public health hazard.