This is purely a product of the post-war boom era. Before the 50s, Americans behaved predominantly the same way - children would even be married while living un

This is purely a product of the post-war boom era. Before the 50s, Americans behaved predominantly the same way - children would even be married while living under the parents roof up into their 30s. But once it was financially tenable in the unique financial circumstances of post-WW2 America for pretty much any man that wanted to could get a job with no education that gave him the financial means to "have it all". Gradually the economy corrected itself, but there is a lot of cultural weight on the idea of success associated with living in your own home, regardless of the feasibility financially.