the example is going to be worth $2.4 million and the couple will have an option to purchase it for $1.811 million. They won't need a large down payment to finance it because of all the built in equity that is theirs if they exercise the option. Their mortgage payment will probably be less per month than they were paying in rent. So they will easily be able to afford it in two years . . . How did you conclude that they won't have "have enough in 2 years to buy the home?"

The other example of how the couple can't save enough works fine. That modest $1 million home they want is appreciating by more than $50,000 a year (and the down payment they need is going up proportionately while they save). They aren't going to catch up even if they are really good savers.