Question: If God knew satan would fall and man would fall, why did He create to begin with?
Answer: God does not know things ahead of time, since God is timeless. But God knows the truth regarding all propositions. Which means that God can see the outcome of every course of action or inaction that is possible, and God being Love chose the best course of action He could. That that choice to create as He did resulted in the fall of satan and the fall of man, does not negate that it was the best possible choice he could make.
St. Methodius of Olympus died ca. 311 [I]t is not satisfactory to say that the universe will be utterly destroyed, and sea and air and sky will be no longer. For the whole world will be deluged with fire from heaven, and burnt for the purpose of purification and renewal; it will not, however, come to complete ruin and corruption. For if it were better for the world not to be than to be, why did God, in making the world, take the worse course?
But God did not work in vain, or do that which was worst. God therefore ordered the creation with a view to its existence and continuance, as also the Book of Wisdom confirms, saying, For God created all things that they might have their being; and the generations of the world were healthful, and there is no poison of destruction in them. Wisdom 1:14 And Paul clearly testifies this, saying, For the earnest expectation of the creature waits for the manifestation of the sons of God. For the creature was made subject to vanity, not willingly, but by reason of him that subjected the same in hope: because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God.
Rom.8:19-21 For the creation was made subject to vanity, he says, and he expects that it will be set free from such servitude, as he intends to call this world by the name of creation. For it is not what is unseen but what is seen that is subject to corruption. The creation, then, after being restored to a better and more seemly state, remains, rejoicing and exulting over the children of God at the resurrection; for whose sake it now groans and travails, waiting itself also for our redemption from the corruption of the body, that, when we have risen and shaken off the mortality of the flesh, according to that which is written, Shake off the dust, and arise, and sit down, O Jerusalem, Isa. 52:2 and have been set free from sin, it also shall be freed from corruption and be subject no longer to vanity, but to righteousness. Isaiah says, too, For as the new heaven and the new earth which I make, remains before me, says the Lord, so shall your seed and your name be; Isa. 66:22 and again, Thus says the Lord that created the heaven, it is He who prepared the earth and created it, He determined it; He created it not in vain, but formed it to be inhabited. Isa. 45:18 For in reality God did not establish the universe in vain, or to no purpose but destruction, as those weak-minded men say, but to exist, and be inhabited, and continue. Wherefore the earth and the heaven must exist again after the conflagration and shaking of all things. But if our opponents say, How then is it, if the universe be not destroyed, that the Lord says that heaven and earth shall pass away; Mat. 24:35 and the prophet, that the heaven shall perish as smoke, and the earth shall grow old as a garment; Isa. 51:6 we answer, because it is usual for the Scriptures to call the change of the world from its present condition to a better and more glorious one, destruction; as its earlier form is lost in the change of all things to a state of greater splendour; for there is no contradiction nor absurdity in the Holy Scriptures. For not the world but the fashion of this world passes away,1 Cor. 7:31 it is said; so it is usual for the Scriptures to call the change from an earlier form to a better and more comely state, destruction; just as when one calls by the name of destruction the change from a childish form into a perfect man, as the stature of the child is turned into manly size and beauty. We may expect that the creation will pass away, as if it were to perish in the burning, in order that it may be renewed, not however that it will be destroyed, that we who are renewed may dwell in a renewed world without taste of sorrow; according as it is said, When You let Your breath go forth, they shall be made, and You shall renew the face of the earth; God henceforth providing for the due temperature of that which surrounds it. For as the earth is to exist after the present age, there must be by all means inhabitants for it, who shall no longer be liable to death, nor shall marry, nor beget children, but live in all happiness, like the angels, without change or decay. Wherefore it is silly to discuss in what way of life our bodies will then exist, if there is no longer air, nor earth, nor anything else. (Discourse on the Resurrection 8-9)