Now, could you add on the housing price inflation over the last 10 years? Your calculation assumes housing prices stay flat for the next 10 years, which is a tall order.

Also, what would happen to people with not so well off parents?

The avocado toast meme is six years old now, and people said the same thing at the time (hence it becoming a meme). It's fair to say "actually I don't have any subscriptions and don't buy daily coffee or go to restaurants/bars (including fast food or pickup) or drink alcohol or smoke or use any other drugs" but complaining that $3/day doesn't add up to a down payment was wrong then and it's still wrong now even after the housing balloon of the last few years. Simple math demonstrates this.

If someone's parents were able to provide a place to live until 18, why is 19 suddenly impossible? You don't need to be well off to let your kids stay with you a little bit past legal adulthood. Surely there's room for a couch or a bean bag or something to give them a huge leg up right out of the gate, assuming you were in a marginal position where you otherwise needed to immediately kick them out and downsize.

Some people are going to have rough situations and can't rely on a family at all. Some will need to emancipate before reaching 18. How common is that? If it is common, that seems like the real problem to address.

Well, as the parent poster mentioned, interest on the savings are not taken into account. Furthermore, the inflation in the price of the Starbucks coffee is also not taken into account. So, seems like the logic/reasoning still stands.