Apathy and money are the reasons
Almost half the country's eligible voters choose to not be bothered to vote. But yet many of these same people have tons of time to wait in line for new I-phone or door breaker deals on black Friday. I know, many eligible voters were denied their right to vote, through targeted voter suppression laws. I know its a pain to go through the whole voting process; From registering, finding your polling places, making educated choices, and then taking the time to cast your vote. As a country we should be able to do better then this regardless of party affiliation.
Then there is money. Its king, especially here in the USA. If you have enough, you can have what ever you want. The laws do not apply to you. Don't like the government, easy buy a new one that works for you. Buy ads that spread fear and hate in 15sec sound bites 24/7 on every form of media outlets and as many times as it takes.
If you are part of that filthy rich 1%, you don't need to have everyone agree with your message. 20% will do. Especially if they live in the districts you used your money to create so your candidates can't lose and there are tons of your candidates in tons of new safe places. Half the voters won't be bothered to vote. So you only need worry about the other half and you already control half of that, thanks to money and apathy.
Of course the media outlets are the real winners. All of them. Their revenue goes up every election cycle. No wonder many in the 1% own 99% of our media outlets. They are not wasting their money. They are just transferring it from bank accounts when purchasing politicians.