In the US, why are Americans letting a small portion of the population accumulate increasingly large portions of the wealth?

In the last 20+ years, the richest Americans gained enough political clout to change the tax system so they could accumulate wealth at a much more rapid rate than ever before. The laws were also changed in such a way that it's becoming harder and harder to change the system back. Americans are now less upwardly mobile than ever and rank below citizens in many EU countries in their ability to move from poor to rich. The Horatio Algers of this generation do not exist.

Having lived in the US for 10 years, and the other 3/4 in the UK, but travelled in between to other nations, please be assured, that there are extremely wealthy people in all nations - it just that the US is by the nature of its history and broadcast media, very much in the public eye. It is far more worrying when such behaviour occurs on in nations with little public exposure, leading to suffering amongst the populace - such as in Africa or some nations in the actual Middle East where there is corruption and no democracy to expose such behaviour, so people suffer in silence. However, and this is a big however, in the US, you are expected to pull your own - so those who do make it big are highly regarded, whilst in European nations, this can appear offensive because we tend to look upon excess with disgust for reasons that I am not qualified to answer, but maybe to do with the Christian influence on our culture, where sharing is encouraged and (apparent) greed considered one of the 7 deadly sins. (My experience shows Americans to be remarkably generous. It is just that here in Europe, we tend to spend it whilst we earn it, so to speak, therefore whittling down any attempt to save and retire comfortably, while in the US, they will knuckle down, work hard, make a killing - and then donate to charity when they can genuinely afford to and make a long term difference.) As others have pointed out, it is not so much the accumulation of wealth that is the issue, it is what one does with it. Why die rich?