Because we are powerless to change it.
The corporations have lobbied (bribed) both political parties so hard that both sides work for them.
Any attempt to change the voting system gets shot down because the people in power don't want to change the system, because it benefits them. Why make the game fair when it's rigged in your favor?
Half the country is brainwashed into thinking any social help or reform is socialism (which is pure evil! Helping others is evil!) and a trick from the inept party to try to gain political influence. And the inept party just fails to deliver on any sort of reform because they want to appeal to that brainwashed half of the country.
Any grass roots effort that makes any traction gets shot down by the establishment, usually by rileing up the brainwashed half.
We WANT the change. But even if we could get the brainwashed half to vote for it, the system is so rigged and broken even if we did vote it in they would veto it or change it in two years.