If the argument was "millenials eat out too much", that they are spending $8/meal×3 meals/day×365 days/year = $8760/year eating out, it would be an interesting article.
But the article is entirely about "avocado toast", a meal that, while popular, is not eaten more than once per week even by any millenial I know. Saving $8/meal×1 meal/week×52 weeks/year = $416/year is so laughably far from helping save for the down payment of a home, especially in a market where avocado toast is popular, like Boston, where it would take 100 years.
The article is vapid. It could be summed up as "get off my lawn" but because the author of this content-free piece is somehow employed by the New Yorker, he found it necessary to wrap it in a dozen paragraphs of purple prose.