Just bullet points, not an essay. All don't apply to all.
Why does God allow suffering?
1. To remind us the world is broken and groans for redemption.
2. To do justice in response to Adam's (and our) sin.
3. To remind us of the severity of the impact of Adam's (and our) sin.
4. To keep us dependent on him.
5. So we will long more for heaven and less for the world.
6. To make us more like Christ, the suffering servant.
7. To awaken the lost to their need for God.
8. To make the bliss of heaven more sweet.
9. So that he will get the glory in being our strength . . .
10. . . . and that thereby others see that he is our treasure, and not ourselves.