No one deliberately wants to be unhappy. Some have lived happy lives and others sadly were not able to find happiness in this life.
But there are different views on what happiness means. Some reduce happiness merely to a psychological state. If one attains a certain psychological state marked by pleasant emotions and freedom from fear or worry then one is supposed to have attained happiness.
Another Christian writer, Thomas Aquinas, stated that, "happiness is nothing else but the attainment of the sovereign good” (I.II.4.1). Some identify this supreme good as pleasure or wealth or honour believing that by attaining one of these created goods one will be happy.
What has been revealed by Christ is that God is the sovereign Good. And thus to know God face to face is definitive happiness. Augustine puts it this way: : you have made us for yourself, and our heart is restless until it rests in you” (Confessions 1.1).
Chris Stefanick shares some simple points about happiness in this clip: