Or they do understand, and are willing to make the tradeoff. I'm about to order a pizza. It will be unhealthy, and also delicious.
I both care and understand.
The fact that soda is an easily-consumable, relatively cheap, energy-dense, decent-tasting liquid foodstuff is why I purchase it.
[0]: http://rivergrandrapids.com/the-first-official-us-coin-said-...
The only thing you can really control is yourself and your reactions to things. I don't watch TV, read newspapers, watch football games, browse the web without an ad blocker, or live in a city. I haven't seen an ad in years. When I do venture into the city, I recognize that I must have seen ads, but I can't recall what any of them were; I'm too busy thinking about other things.
Stop blaming other people and focus on yourself.
As for your advice to focus on one's self, maybe you should try taking it.