My perspective is that we're reached our current sorry political state mostly because we've failed to properly educate ourselves, and especially our children, for several generations now.
The resultant ignorance leaves/left us vulnerable, as a society, to manipulation by the full spectrum of propaganda techniques. Propaganda has become a scientific discipline, and with that it's now much more effective, deceptive, and cost-effective than it used to be. Another way to look at all this, is that societal education, in our "democracy", has failed to keep up with the advances made in the science and application of propaganda.
The result is that "big money" has gained significant control of most of our levels of our governments through the expedient of buying the people who comprise government, both through funding election efforts and also by social-engineering propaganda designed to promote selected ideologies favorable to oligarch's gaining yet additional power and control.
Oligarchs have used the increasing control they have gradually achieved to further enrich themselves, and to solidify the control they have gained, and gain ever more control. They have significantly modified our rule of law, and especially regulatory framework, so as to slant the prior balance of power between labor and capital towards capitol and against labor.
The result is that income and wealth inequality in the U.S. has increased dramatically over the last few generations, as measured, for example, by the gini coefficient. The gini coefficient is a measure of income inequality. As can be seen on Wikipedia, U.S. gini has increased from around 35 in 1970 to around 45 now (https://en.wikipedia.org/wiki/Gini_coefficient). This is a HUGE and highly significant change; among those countries included in the plot, our only piers are now Brazil, Mexico, and China -- not exemplary for a supposed democracy.
This is a telling increase, representative of our move towards becoming a third-world country; I might add that our gradual migration towards third-world status (albeit the richest third-world country on Earth) shows up in a wide variety of socioeconomic, health, and social-welfare statistics. It also shows up here (http://www.epi.org/publication/raising-americas-pay/), another facet of more or less the same thing.