What are the wisdoms behind tribulation?

Trials for people have great wisdoms, among them: realizing servitude to Allah, preparing believers for empowerment on earth, expiating sins, elevating ranks, providing an opportunity to reflect on one's own flaws and mistakes, serving as a lesson in monotheism, faith, and reliance on Allah, removing conceit from souls, revealing the true nature and character of people, nurturing and preparing men, distinguishing true friends from fair-weather friends, reminding of sins to repent from them, exposing the reality and falsehood of this worldly life, reminding of the blessing of Allah's favor of health and well-being, and creating a longing for Paradise.