Buying home is less of a financial decision and more of a lifestyle decision.
This is as it should be.
When it comes to having the extra cash, I am not sure that on average, it would be extra at all, meaning that the majority of people will expand their lifestyle and consume it, not invest it to generate income now or in the future. If we look at the lifestyle of a student who can live off little and still get drunk, that habit doesn't seem to change as the same student earns in a career - they still get drunk on the excess, though it might not be cheap beer and condoms :)