You know Britain is becoming poorer, the people broke, when

[Zero Liability]

People aren't very rational.

That's because it's a loaded term, and usually what is implied is that people don't spend much time researching their decisions, which is true to some extent, and certainly true in politics, where the incentives are skewed against the voter actually doing so.

The Millionaire Next Door is a fun read on the consumption habits of the rich, but it's written with a US focus.