The key to house prices s which dollar they are using to do the calculations. Obviously it is todays dollar which will not be worth as much in 10 years time so the doubling in price is part illusionary. However it gives us incentive to spend our current dollars and buy real estate. One of the big, hidden drivers of house price rises are the migrant arrivals who think little of having 3 families sharing one home. This is common in the big cities ie London. This enables the cash flow to pay inflated prices for property as the rent return easily pays the finance. Melbourne is a good example as it has a large number of "students, tourists" etc in the process of getting residency status. This gives a huge buying side as they are funded from overseas as the platform for more relatives to get residency status. As a further example it is common in Pakistan to add another floor to a building as the extended family grows. So you have an 8 storey house with maybe 60-70 people in it. That is an enormous source of money to finance one person to establish in another country. So the house price rises are not all coming from Jack and Jill setting up house together.
