If Allah has decreed it, it will happen. However, you have to believe that Allah is fair and just.
Allah has created the people and gave them the will to choose. Those who choose wrongly will be thrown in hell. They can’t complain that this is Allah’s will as they didn’t know what Allah’s will was before choosing what they chose. Such people, we challenge them to throw themselves from the roof of a high riser. If Allah wills it, they will fall on their feet unharmed.
No one would agree to do that because they will tell you: we are no insane to do such a thing.
Likewise, you choose whether to do good or bad and Allah will reward you or punish you accordingly.