A summary of today The questions you raise are so complex and multi-faceted that I'll have to be a bit overly simplistic.
What brought us to this state is the triumph of the American Empire (let's call it AE). AE became the dominant global power in the aftermath of WW2. And following the collapse of the USSR, AE's global supremacy was basically unquestioned. However, America doesn't like to think of itself as an empire. AE doesn't conquer nations or set up colonies. Rather, it rules by trade. AE dominates other countries by giving them no other option than to business with it. And when you do business with AE, you do business on AE's terms.
In a lot of ways, America does a much better job at ruling than its imperial predecessors. It goes to war less frequently than the Romans did, and it doesn't violently impose its culture upon other peoples the way the British did. But because Ae rules through economic might, it's caused wealth and power to become nearly synonymous. And that, I think, is why we are so obsessed with filling our coffers and raising our GDPs no matter the human cost. Under the current global order, money makes the world go round. You can't do anything without money. All the noble objectives you want to accomplish require an enormous amount of money. And in order to get that money, you need to act like a greedy soulless capitalist.
So that, I think, answers the question of why we're in this state. But the question of how to make a change is far more difficult.
I strongly believe that socialist revolution is not the answer. For one, it hasn't worked in the past. And I don't see how it ever could. If you give the government enough power to radically redistribute the wealth in society and centrally manage all large scale economic activity going forward, they will almost certainly abuse that power. And if you think that power can remain with 'the people,' you should read Animal Farm. I could write a lot more about why socialism (even if it's democratic) isn't the answer. But for now, I'll focus on what I think might be a better answer. Because America is the source of the problem, it also has to be the source of the solution. Of course, we could just try to destroy America, but that would probably end in massive wars and global chaos. So let's cross that off our list.
I think you're right that we need better leaders. But how do we make them better? I don't think we can just educate a generation of exceptional people who will naturally take charge and fix our problems. What we need to focus on is changing the aspects of our system of government which cause our leaders to make bad decisions. And when we think of possible changes we could implement, we should make them as realistically achievable as possible. So we can't just design a new system of government.
I'm sure there are many flaws in our system that we should try to change, but I'll focus on one for now.
Our politicians are too dependent on special interests. But we can't just get money out of politics. Corruption will always find a way to creep back in. We need to adjust the rules of democracy so our politicians aren't so desperate for donations. Right now in America, Democrats and Republicans are fighting with everything they've got to maintain their power. And in order to win, they need money. They need to act like corrupt, morally bankrupt traitors who care more about undermining their political opponents than serving their country. This dynamic is tearing America apart. It needs to end. And the only way to end it is for one side to win and the other to lose. It's too late for us to come together. We don't need a total victory where Democrats absolutely wipe out Republicans or vise versa. We just need one side to dominate the other enough so that the two can reach an understanding about who has the power. Following WW2, the Democrats had all the power. From the early 50s till the mid 90s, they never once lost their majority in Congress. During that period, the Republicans understood that the only way they could have any influence is if they cooperated and sometimes even went along with the Democrats.
But given the current demographics of America, neither side can dominate the other. So both sides have to bend to corporate interests in order to raise enough money to win elections. Both sides have to refuse to compromise in order to satisfy the people who vote for them and give them money. What we need to do is change the rules so that one side has a clear advantage. We shouldn't change the rules too much, because that might cause political instability and make the situation even worse. And we should change the rules in a way that makes sense, seems justified, and isn't just clearly ad hoc. If we do that, we'll at least be capable of having effective leaders. And maybe these new leaders will be able to address some of the problems you're talking about. And whether the changes to democracy should result in Democratic or Republican leadership... I've already written too much, so I'll save that part for later.