Ive had some people ask me to talk to loved ones and share my knowledge of nutrition etc to help them improve their lives.
I keep explaining to these people I cant force my knowledge on them, they need to want it and be receptive to it and give it time otherwise I am just wating my time and theirs.
Some come around, most dont. You can lead a horse to water but cant make it drink.
I try and save my time and energy for those who truly want better health. I wouldnt waste my time trying to change the OP's mind because as you said, they are clearly snowed. Ill reserve my energy for those with a more open, logical and sensible mind.
Being heavily involved in canine rescue I have long ago accepted that I cant save them all and my energy should go toward those that I can.