Massive tomes have been written about the devolution of Western civilization. Many are insightful and interesting. I wonder, however, if the collapse is more simple than many imagine. Perhaps understanding it can be achieved by a knowledge of "common sense" virtue.
The decline and fall of the West is a story of hubris and pride. With little question, Western civilization is the greatest that has ever existed. No other civilization remotely compares to its achievements in most categories. No other civilization has had such an effect upon every other. This rise has been so rapid and so great that it has destroyed most of what humanity formally believed. The idea that man would one day stand on the moon was so far from most of our ancestor's minds they could not have understood the possibility.
Such a meteoric rise has consequences. Like most men who achieve unprecedented success (and especially their children) there is the threat of pride that reduces their reliance on traditional understandings of life and its limitations. There is the temptation to defy rules and abandon inherited wisdom.
Celebrity rebels are typical. They flaunt the law, conservative values, and social mores because they can. They have the wealth, fame, and success to get away with defiance without suffering too many consequences. They possess a hubris which makes them believe they are above social and natural systems. This pride, however, often leads to their downfall. They become addicted to drugs, are arrested for disorderly conduct, destroy their careers, and sometimes lose their lives.
In Hosea 7:10, the prophet tells us the Nation of Israel had become an arrogant ethnos. Civilizations, like rebellious celebrities, can grow powerful and prideful. They can rebel against God and nature because they imagine they have superseded the rules and possess the ability to defy them. Western civilization has been powerful for long enough that our people no longer believe themselves limited to the laws of nature's God. It is the abandonment and rejection of God's established order that lies at heart of every point of decline.
The white ethnicities that built Western civilization now believe ourselves invisible. Throughout history, nations understood that survival required defending their borders and protecting their identity lest invasion and conquest erase their existence as a people. Today, Euroethnics no longer believe we can be erased, or that our societies can fail. We believe, contrary to traditional wisdom, that we can allow millions of ethnic "others" to pour through our southern borders (in both Europe and America) without losing our grip on stability and cultural hegemony. The claim that we no longer need to defend ourselves from our enemies is the height of hubris.  It is prideful delusion to believe that we are immune to the development of historical conquest and war and that the ethnic groups entering our lands will embrace our ideologies.  Unless we humble ourselves into taking up arms to defend our family members, friends, and nations from the migrant invasion we will see our civilization submerged under a flood of people who know they must play by nature's rules. The Third World's teeming hordes understand that they are not above fighting to survive; we, in the First World, are so consumed with our "superiority" that we have the privilege to assume ourselves morally above fighting for our interests. We may believe ourselves invincible, but the law of God will humble and possibly destroy us for disobeying the ordinances of human existence. The Noachic Covenant of Genesis 9 established the modern order of violence, justice, and survival. We cannot overcome what God has ordained.
The modern West's obsession with equality has led to the denial of reality. In America, for example, Afroethnics are asserted to be equally intelligent as Euroethnics and East Asians despite all known evidence and experience repudiating this claim. Anyone who speaks the truth about ethnic differences in intelligence is ostracized from society. The West has proclaimed itself greater and wiser than nature's laws and genetic reality. The effort to "close the achievement gap" has cost our societies trillions of dollars in wealth, and ethnic integration has resulted in horrible atrocities against our people.  The laws of nature will eventually prevail regardless of our hubristic assertions.
The West has proclaimed itself sexually liberated and discarded several millennia worth of accumulated reproductive wisdom. Now, even the difference between males and females is contested. Our society would proclaim women to be men and men to be women. Never has any civilization in human history attempted such a psychologically disturbed program. It represents the zenith of arrogance that we could ignore reality and exist as we wish without regard for the truth of our genetic identity or the biological categories nature has defined. This rebellion has led to the horror of surgical and hormonal suicide in which millions have destroyed their identities through farcical games of pretending to be members of the opposite sex. Millions of homosexuals no longer reproduce in the natural way. What society has ever survived its population's refusal to create the next generation?
Modern landscape scarring, also known as contemporary "architecture," is a form of hubristic obsession with building new and different things while intentionally rejecting the proven beauty of the past. Instead of placing man within a historical place and time, this style of construction removes man from his history and destroys his identity. It intentionally replaces past wisdom with the prideful obsession with the new. These architects seek to create structures that arise from within themselves rather than serve the interests and tastes of those who will use the buildings and inhabit the space.
The general chronocentrism of the modern age is a form of arrogance that has led to the dismissal of traditional wisdom as "outdated," "irrelevant," and "oppressive." Religious belief is among the ancient wisdom being dismissed in favor of humanistic ideologies that proudly proclaim man the definer of nature, history, and meaning. In short, Western civilization will fall because its people believe themselves great enough to flaunt the laws of history. They have pridefully chosen to overextend themselves behind their capacity to maintain, and beyond the boundaries God has established through nature. Pride will cause the collapse. We believed ourselves capable of doing things we could not do. We thought we could defy God and nature and survive. We will soon be humbled.
 Scot, Tory. "American Icarus." The Right Stuff. March 20, 2016. Accessed March 21, 2016. http://therightstuff.biz/2016/03/20/american-icarus/.
EXCERPT: "This hubris that makes [liberals] believe that we are so great that we can change everything, and, more importantly, everyone, to fit into our civilization will be the end of modern liberalism, in both its "left-wing" and "right-wing" incarnations. Conservatives want America circa 1950, and progressives want to turn the entirety of America into Portland, but the reality of the ongoing replacement of the children of the West means we are going to get neither. America's future isn't Portland. America's future is Detroit and California, with all the accompanying corruption, ethnic pandering, crime rates and low trust. Enlightenment values aren't practiced by Blacks in the Congo, or by Mestizos in Mexico, and they won't be replicated by them here."
 Consider Francis Fukuyama's "The End of History and the Last Man." The book claims Western liberalism will end history by pervading the culture, institutions, government systems, and academia of every ethnic groups and state on earth.
 The erasure of South Africa's white ethnic Boars is an example. Afroethnics have been carrying out a genocide against our people in South Africa since the fall of Apartheid. In America, African-Americans disproportionately target Euro-Americans as victims for violent crime.