I have done the avocado toast math, if you save an average 7$ a day and put it in an account with 3% interest over 45 years you will end up with 233K$ savings. (Inflation would increase a future house price and your necessary savings).
I think it would be reasonable to include inflation directly, say we are very optimistic on the investment strategy, so 4%, or 1.92% after 2% inflation, per year.
It's unreasonable to expect someone to wait 45 years to buy a home - A young millennial (now 25) would have, in average, another 10 years to appreciate the purchase before dying. Not exactly a worthy investment. A reasonable limit, I think, for a long-term investment would be 20 years.
So, 30$ a day would need to be saved consistently, every day, in what I consider an optimistic scenario. That's quite a lot, for the majority of people.
I also don't think that there is really such a strong overlap between the people frequenting trendy cafés and those complaining about the difficulties of buying a house. I'd say the former are largely spoiled brats who'll end up getting the necessary funds from daddy, regardless, if push comes to shove.
Bet with PeH:
I win if Arms sells over 700 000 units worldwide by the end of 2017.
Bet with WagnerPaiva:
I win if Emmanuel Macron wins the french presidential election May 7th 2017.