Dr. Sanity admonishes those who try not to think too hard:
For those of you who think all this philosophy business is too abstract and irrelevant to your life; you are very very wrong. Catastrophically wrong.
These ideas have everything to do with your life and how you live it. They are also the crux of why the world we live in seems to be more and more incomprehensible and insane. When you start off with the belief that reality doesn't exist outside your own head, then, it is just a very short--and minor--leap to accepting that words don't matter and can change meaning; or that it doesn't matter how you behave; that everything is relative anyway, including truth and morality.
If everything is relative, everything is meaningless. And not in some care-free hedonistic way. Without fixed meanings there can be not trust. Without trust there is no cooperation. A post-modern politcally-correct all-inclusive world is not sustainable. It is de-civilization.
Building civiizations takes centuries. It is a slow process; nobody goes to sleep in cave and awakens in a loft condo. Decline might be faster, but still slow enough for most not to notice. Sudden tragedies temporarily spur cooperation. Earthquakes and wars lead to rebuilding. Slow tragedies kill us while we sleep.