Both dissatisfaction and boredom are conditions of meaninglessness. So either way, our lives turn out meaningless. The key premise of this argument is that we will either achieve our goals or we will not. That is true of everyone. Basically, the relentless passage of time and the vastness of the universe show me how little significance we have in it.
Time erodes all value.
Nothing in the past has the value it once had when present. This is shown by how we treat history. If the past had any real value in itself, we would care for the truth about the past. But history is determined by present needs and ambitions. Take, for example, the Pocahontas story as told by the recent Walt Disney movie.