The Buddha realized that life as usually lived is characterized by an underlying suffering, malaise, sense of unsatisfactoriness, Kierkegaardian anxiety, Sartrean anguish or Heideggerian forlornness. However, where he diverges from the three latter thinkers is in refusing to claim that such a condition was necessary.
The Buddha was not superficial in his analysis, but extremely thorough, as the Suttas of the Pali Canon reveal. He knew that not only the three mental conditions of clinging, aversion, and self-delusion can cause suffering, but also physical conditions such as being deprived of food, water, shelter, adequate basic clothing, and other such conditions.
The physical causes of suffering must be addressed through physical solutions; the mental causes of suffering must be addressed through mental solutions rooted in, for instance, mindfulness, detached witnessing, recognition, meditation, contemplation, and the cultivation of virtuous habits and insight.
Moreover, the the more we move out of our own personal suffering, the more we can attend to the suffering of others with sincere, not condescending, compassion.
Some have claimed that Buddhism is an otherworldly and escapist philosophy, but the truth of the matter is that the Buddha confronted the natural order of things and looked deeply into the matters of death, sickness, old age, and other causes of human misery. His philosophy is focused on encounters, mindfulness of lived realities and facing facts, however unpleasant they may be. It is not an escapist philosophy.