Does DC's background and wealth matter? I think it does.
Here's an example of why, from the other end of the spectrum: there's a property porn thread that's active at the moment, where people are posting links to the dream properties they'd buy if they won the £85m lottery tonight. Quite a lot of the links are to houses worth 900k, £1.1m, £1.4m. That's because for many people, it's really astonishingly difficult to imagine their way into a lifestyle very very removed from theirs - to get their heads round what £85m really means.
DC would have absolutely no problem imagining how to use £85m and what kind of property he could buy. It's a step up from him, but it's won't feel outlandish: his and Sam Cam's assets are almost certainly well in excess of £10m, and there's no doubt that being PM is a significant pay cut for him compared to what his peers earn - and I'm talking about total pay package which includes not only the £140k property but two grace-and-favour properties, car and driver, etc etc - well over £500k pa in value.
His problem is the other way round: he'd struggle to really feel in his guts what it's like to worry about how to pay the school fees, as people earning "only" £100k in London do.
The notion of actually worrying about £20 for food this week will be completely unreal to him.
Here's how it works (based on earnings alone, not wealth, so it's actually more distorted in reality):
DC will compare his earnings with his peers - there are about 300,000 people earning between 100 and 200k pa who you might think of as his peers, and they are, nominally. But his real peers are the 89,000 people earning between 200 and 500k, the 16,000 earning 500k to £1m, and the 6,000 people earning £1m+. He will personally know quite a lot - hundreds - of the 16,000 and the 6,000. They are the celebs, hedge fundies, PE folks, property developers, aristos, accountancy partners, business execs etc who he spends his social time rubbing shoulders with and his working time doing business/government with. So he'll tend to look up, to these people.
The 11.4m people earning between 20 and 100k are decidedly not his peers, and as for the 18.5m people earning between 5 and 20k, they are on an utterly different planet.