Watch this excellent video which illustrates something that many people find difficult to picture - the extraordinary inequity of wealth distribution in the developed world. This graphically represents US inequality:
The US is close to the most unequal country in the world, by wealth; here's the key graphic again, this time from Mother Jones:
Now, things aren't so bad in the UK, so I thought I would just re-draw that top graph, the actual distribution of wealth, for the UK*, for comparison:
EDIT: The UK figures are - Top 20% own 69% of the wealth, next 20% the next 18% (top 40% own 87%), next 20% the next 9% (top 60% own 96%), next 20% the next 3.5%. The bottom 20% own 0.5% (that's half of one percent) of the country's wealth. That's right, the bottom 1 in 5 only own a two-hundredth of the wealth, and the bottom 2 in 5 only own a twenty-fifth of the wealth. Half the population own less than a tenth of the wealth. I think, apart from the measurable bad outcomes that result, everyone with a sense of fairness would concede that is not fair, as the bottom chart shows.
For the reason why this matters, check out the Equality Trust.
* I calculated the figures from this data, which listed the wealth of each percentile except the top 1%, for some reason (ungraphable!). I guestimated the wealth of the top 1% from this article, which cited data saying they owned 25% of the wealth in the UK (it's 40% in the US, according to the video above). Not terribly scientific I agree, but I doubt the actual figures are much different.