I know that Allaah The Almighty knew the destiny of every human being before creating them, that is, whether he is from the people of the Paradise or the people of the Hell.
So, why did He create man?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Allaah The Almighty has created this life for testing His servants, by sending the Messengers, may Allaah exalt their mention, and revealing the scriptures. Therefore, whoever believes in the Messengers, may Allaah exalt their mention, and applies the scriptures will be from the people of Paradise and whoever disbelieves in the Messengers, may Allaah exalt their mention, and abandons the scriptures will be from the denizens of Hell.

The Prophet, sallallaahu ‘alayhi wa sallam , was asked about what humans did in their lives;  had it been predestined or not? He, sallallaahu ‘alayhi wa sallam, answered  that it had indeed been predetermined for them. Then, he, sallallaahu ‘alayhi wa sallam,  was asked about the benefit of striving in this world in order to be from the people of Paradise.  He, sallallaahu ‘alayhi wa sallam, commanded that everyone should strive in this world because Allaah The Almighty has eased for every man to do the deeds that would lead him to what he has been created for. In other words, the people who have been predestined for prosperity would find it easy to do the deeds that would lead them to be prosperous, and the people of wretchedness would find it easy to do the deeds which would lead them to be doomed. [Muslim]

Allaah The Almighty Says (what means): {Indeed, your efforts are diverse. As for he who gives, and fears Allaah, and believes in the best [reward],  We will ease him toward ease. But as for he who withholds and considers himself free of need, We will ease him toward difficulty.} [Quran 92:4-10]

Hence, everyone should strive and search for the correct guidance and supplicate to Allaah The Almighty to keep him  steadfast to the true religion. Furthermore, everyone should know that  Allaah The Exalted has always known what His creation will attain, how long they will live, and what they will do.

Nevertheless, we hardly see people questioning what they are meant to attain, while most of them question whether they are meant to be doomed or spared, although they are all similar issues of the unseen.

A wise man must not use the fact that Allaah The Almighty knows the destiny of every one of his creatures as a pretext for not observing proper acts of worship.  Allaah is All-Powerful and  All-Knowing, and it is only logical that our Lord and Creator must  know everything about His creatures. Allaah  created us and He  knows the future of his creatures, whether they will obey or disobey Him, and whom He will punish and whom he will reward.  Allaah The Almighty Says (what means): {Does He who created not know, while He is the Subtle, the Acquainted?} [Quran 67:14], and He is the One who does what He wants without being asked or questioned by any of His creatures. Allaah The Almighty Says (what means): {He is not questioned about what He does, but they will be questioned.} [Quran 21:23]

Allaah The Almighty also told us that He has created man and Jinn only to worship and obey Him; He Says (what means): {And I did not create the jinn and mankind except to worship Me.} [Quran 51:56] Moreover, through creating man and Jinn and testing them with the religious duties to be either rewarded or punished in the Hereafter, Allaah's creation can come to understand the  attributes of Allaah The Almighty.  Allaah  is the Creator, the Sustainer, the Giver and Taker of Life, the Merciful, the Ever Merciful, the perfectly Wise, the All-Knowing, the Supporter of the believers, the Disgracer of the disbelievers, the One who Judges His servants and rewards or punishes them for their deeds, the Avenger, and the Irresistible who avenges for His worshippers from the disbelievers. He is the Owner of perfect justice and benevolence.

Thus, a Muslim should not preoccupy himself with such a question, because this may eventually lead him to lose his faith, rather we must trust in the Justice and Wisdom of Allaah the Almighty, who would never punish a slave if he did not commit a sin he committed, and who forgives many sins. This could only be achieved through complete surrender to the judgment of Allaah The Almighty whether or not we recognize the rationale behind it and the belief that any defect or flaw is in us not in the judgment of Allaah The Exalted, who Says (what means): {He is not questioned about what He does, but they will be questioned.} [Quran 21:23]

Allaah Knows best.