Seeing the thread title, over and over, it's the sort of vain and presumptuous question somebody may ask with no understanding of God. Sure enough, it's like a gateway drug to Adventist or the like false teachings of soul sleep and annihilation.
The question as to "why" any such thing, that questions God's nature or character, violates the Lord's clear admonitions at the end of Job, asking who are you to question the Creator? It's a presumptuous creature question, from somebody lacking the humility to realize you may actually know nothing, in your vast experience of living a few years, compared to the eternal Creator. Perhaps you aren't quite equipped to judge God? Is that possible?
As to hell, it's just what scripture clearly states, and states in enough places to understand it's a place of eternal punishment. What you don't understand is, in fact, completely immaterial. Maybe you should be presenting questions as to the fear of the Lord you don't seem to respect, or trusting the Lord in those things you don't understand? Instead of foolishly trying to put God on trial, could be you'd be wiser to be concerned over your own trial.
Proverbs 9:10 The fear of the LORD is the beginning of wisdom: and the knowledge of the holy is understanding.