Karl Marx was the foremost hater and most incessant whiner in the history of Western Civilization. He was a spoiled, overeducated brat who never grew up; he just grew more shrill as he grew older. His lifelong hatred and whining have led to the deaths (so far) of perhaps a hundred million people, depending on how many people perished under Mao's tyranny. We will probably never know.
We will not wish we had made more money, acquired more stuff, lived more comfortably, taken more vacations, watched more television, pursued greater retirement, or been more successful in the eyes of this world. Instead, we will wish we had given more of ourselves to living for the day when every nation, tribe, people, and language will bow around the throne and sing the praises of the Savior who delights in radical obedience and the God who deserves eternal worship.