Life is defined by human nature and individual behavior. I believe it is human nature to seek happiness, but if we seek it in the wrong places then eventually we're going to turn up with nothing, leaving you dissatisfied with your choices and unhappy with your perception of the world. This behavior would lead most people into thinking the world is cruel. But if you look in the right places for happiness, everything will unfold as it was naturally meant to be.
Every good choice you make can change your life. Every bad choice you make can change your life. If you aren't happy with how things are turning out, you are the one to blame. Think about that next time you complain that the world is a horrible place and nobody can win.
Life is what you make it, and how you see things if you see the world as a cruel place then you are only going to focus on the bad instead of good. Life is subjective to whatever you bring to the table. So make sure what you bring to the table is good!