I have posed this question in several forms over the past few years. In his latest, Publius Decius Mus offers an excellent exposition and answer:
Comprehensive Conservative Failure
If I may address professional conservatives directly: It seems to me undeniable that you have already failed. Don’t take it personally. I can rephrase that as “we” if you like, even though I was never much of an operative within Conservatism, Inc. But I was a fellow traveler and supporter, so if you want to lay part of the blame on me, fine.
We failed. We didn’t do what we set out to do. We lost the political and culture wars decisively. Our economic victory turned out to be fruitless: all the gains have accrued to those we nominally “defeated,” as evidenced by the fact that the Democrats are now the party of the super-rich. Our victory in the Cold War also turned to ashes, as we lost our heads pursuing unrealizable foreign ambitions while fighting in ways that preclude the possibility of victory. Not that we know what victory entails or have any idea what to do with it if we achieve it—but that doesn’t matter, because since 1991, we never have. Worse, we were crushed in the war of ideas:
It would not be the first time that a nation, defeated on the battlefield and, as it were, annihilated as a political being, has deprived the conquerors of the most sublime fruit of victory by imposing on them the yoke of its own thought.
You don’t have to be alt-right to see that this is a perfect description of the USSR’s posthumous intellectual victory in the form of “Cultural Marxism.” Climb down from the egghead mountaintops and the defeat becomes even clearer. A principal Soviet export was crude anti-Americanism—grounded in high theory, to be sure, but simplified to be understandable by even the meanest capacities. We “won” the Cold War, but that export nonetheless spread like a virus—so much so that anti-Americanism is now and has been for at least 20 years the civil religion not just of all Third World populations, not just of Western allies, but of American elites and their foot soldiers.
We failed to preserve a true understanding the principles of the Declaration of Independence. We failed to preserve the proper working order of the Constitution. We failed to protect and nurture that virtue in the people necessary to sustain the Constitution. We failed to defend the family from relentless assault. We failed to maintain any semblance of a shared public morality. We allowed—through a combination of active cheering and ineffective opposition—demographic and cultural replacement. We lent a great deal of our talent to serve rapacious interests in the name of “economic freedom.” All the things we were supposed to conserve—the nation, its people, its way of life, its governing structure—we have not conserved.
This is exactly right. It also helps explain the rise of Donald Trump -- and why you ought to vote for him despite his manifest negatives. He is our only hope to stop, or at least impede, America's leftward slide into oblivion.