Basic simplifcation: A large amount of future income for people is going to go towards a house. It’s not so much that the house price not going up causes the collapse in QOL but that it’s a sign of it’s falling or in the case of right now not keeping up. There is a total of 12 trillion dollars owed on mortgages in the US, in a country that’s gdp is around 26 trillion and the average mortgage has somewhere around 15 years left it’s easy to see how that ends up being a reflection of bad things.