Why did god create men?

Having Satan as a good example as to how things can go absolutely wrong, why did he create Adam & Eve and allowed them to create even more beings that could become the 2nd, 3rd, etc, Satan? Satan was an angel, and if even he could become evil, much less a lesser being, men. As if the creation of Adam & Eve is not bad enough, he planted the Tree of Knowledge to tempt them. If he did not have the tree in Eden, there will be no temptation and subsequently punishment on humankind. - Thoughts after reading the bible and John Milton's Paradise Lost