On every HN thread about meat there are people claiming they know dozens of people that nearly died because they stopped eating meat, completely neglecting that there are entire cultures that eat pretty much no meat[0]. Or the fact that there are numerous studies about how we eat too much meat and how it affects our health[1]. Sorry, I just don't believe it. Or my experience is just vastly different, because nobody I know that went vegan had side-effects as described by these comments. It's like you said, getting your nutrients on a vegan diet is trivial nowadays, especially if you live in a developed country. The only explanation I have is that people are scared to lose their burgers.
Vegan and vegetarian are pretty different. I don't have a problem staying healthy (and enjoying a dinner or two out every week) without meat, but I think it would be extremely hard for me to do that and keep vegan. As I'm allergic to nuts a decent chunk of common substitutes are off limits.
Is it still possible? Sure, but giving up dairy/eggs would be a much bigger sacrifice to me than giving up meat, and it goes beyond just enjoying the foods - the effort required to maintain a balanced diet would have additional time and social costs that vegetarianism doesn't for me.
I think a much more fruitful avenue for persuasion (and this applies to vegetarianism too) is to encourage people to try cutting back on the products, perhaps start with one day a week meat-free. Different people may find it easier or harder based on a number of life circumstances, but the easier they find it, the more they may cut back.
[0]: https://en.wikipedia.org/wiki/Vegetarianism_by_country [1]: https://www.ndph.ox.ac.uk/news/new-study-finds-links-between...