Tribulations come because of the greediness of men. Men are so greedy. They spend so much just for pleasure. There is no sense of concern in people. They do not have the love to share what they have to better the life of others. Everything that they are now is pleasure.
The resources of the earth would have been enough to sustain everyone. It is because some people have been living in greed that is why some others suffer. The suffering in the world is due to the love for pleasure. Our body loves pleasure.
Though tribulations are sometimes painful, they are good in shaping our lives. We become better people when we have persevered through some tough times. Life in the world is not altogether convenient but we do understand that the plan of God for our lives is good. So, we endure even in the face of tribulations.