Sure, the math doesn't add up. An avocado toast and a coffee every morning won't add up to a real estate deposit. But that's not the point; the point is that people who are barely making ends meet having avocado toast at a coffee shop have the wrong mindset. I'd argue they are barely making ends meet because they're having avocado toast at a coffee shop, and multiple other expenses they can't responsibly afford. I've worked with young people barely making any money out of school, who still religiously went to the pub with their mates for the proverbial pint, and never skipped on Costa del Sol holidays.
I grew up in a lower-to-middle middle class household. Eating out was something we did on special occasions (some birthdays, high school graduation, etc). Travel and holidays were limited to the one holiday a year, to a beach 45 min away from where we lived. It does seem like young people these days have an incredibly distorted sense of what they "deserve" or what they can afford or what's "normal".
Now after decades in tech, a couple of stints at FAANG, I'm pretty comfortable financially. There's a lot of things I can afford in the strictest sense of the word (a 300k Lambo, a boat, whatever), but I know better than to spend money on things I don't really need just because I have enough money to buy them.
Love avocado toast but are on minimum wage? Go to the store, buy bread and avocado, make your own goddamn toast, and organise a picnic with your friends in the nearest park.