The risk our republic is pretensed on is totally worth it! As long as we the people remain a virtuous society, we will continue to flourish with a limited government. And the wonders of our limited government includes natural rights which our government is powerless to interfere with, free enterprise and all sorts of built-in mechanisms designed impede government tyranny. On the flip side, as our friend Big Ben Franklin said, only a virtuous people are capable of freedom. The minute we stop being a virtuous society, the American system fails (which is what we're seeing right now). Where you and I disagree at is whether an unvirtuous society should get its just deserts for engaging in the kind of foolishness that leads to special interest groups having so much sway (or an unelected bureaucracy having so much power). I have no problem with this whatsoever. We had a choice. If in the end, it turns out we chose . . . poorly, so be it. Reap the consequences and hope the next generation isn't doomed to repeat our mistakes!
We can agree that a Democracy can temporarily function under a virtuous society. However, the institution of Democracy enables disvirtue (for the lack of a better term) to spread and take over existing institutions. This is not only because human beings are naturally evil, but because disvirtue is more appealing as it is often grounded in hedonism. If people can throw away old traditions and institutions because it feels better, it is likely they may do so as a general population because humans are naturally evil when left to theirselves. Much like how humans resort to murder and extreme violence under the lack of enough government.
Think about modern day degeneracy like feminism, BLM, self-hate and guilt, cultural Marxism, rabid materialism/consumerism, LGBT, and of the like (which I assume you will equally despise as I do being a Conservative). These things became a thing because there wasn't enough force put down on them. A democracy gives these people voice. An authoritarian government or Monarchy would always keep them suppressed.
Because it comes the closest to people having the ability to live their lives the way they see fit without someone else telling them what to do. Freedom if you will. As to this notion that society lasts longer under a monarchy (or hell, lets just call it what it is since I'm rejecting any form of leadership under which one man/woman has absolute power), I've (1) seen no proof of that and (2) don't count longevity alone as being indicative of a good society. There are barbaric cannibalistic Indian tribes who've maintained their traditions for generations, but I wouldn't consider that as being indicative of a good society to live in.
Freedom is valuable why? The freedom to resort to immorality and hedonism is NOT a freedom that should be granted. Morality, law, and order are much more desirable traits in a society than the freedom to violate morality and traditional social norms.
1. No proof? How about Europe before the enlightenment ran loose? Europe was advancing in almost all aspects, scientifically, economically, technologically, etc, long before Classical Liberalism.
Or how about the great empires throughout history? The Eastern Roman Empire lasted for 1000 years. The Chinese dynasties lasted fairly long and would rise again if they ever fell. The oldest Republic I can think of (that is a complex society rather than a homogeneous micro-state) is Rome, which "fell" and rose again in despotism only because it ditched Republicanism that caused its issues.
2. Longevity can often be evidence of societies being strong because they can ward off enemies and not collapse due to internal issues. Your assertion about native tribes is a largely biased and overgeneralized assumption about Native Americans. Regardless, these societies would eventually fall to Native American empires and then the Europeans. Moreover, the civilizations of the Americas are a weird exception to a lot of things because of how isolated they were from the world.
Perhaps a historical example would be more instructive. Tell me, which monarchy throughout say . . . all of human history, got it right? Whose regime would you like to see the US model itself after?
Tough question, as I don't believe any single historical model should be the precise basis for American government. However, I do believe something similar to Imperial China or the Eastern Roman Empire is a good starting point.
We the people of course. And on that front, we've failed and are thus currently experiencing the government we deserve. We have the built-in mechanism in our Constitution to stop all of this however. It's simply a matter of whether we have the will to exercise it.
We can theoretically stop this, but not practically. Most people aren't going to try to save and rebuild things. Most people will just live their lives. This is why a hierarchy is necessary.