Adam and Eve had everything in Paradise except permission to eat from the tree. Hashem wanted to see how his new creations would work, so he tested them as weakly as possible; giving them (only) % 99.99999999 of the universe. Hashem needed to know if man would be able to be live satisfied without having 100% of everything. In Pirkei Avot (Ethics of the Fathers) we learn that a rich man is one who is satisfied with what he had. Human nature, however, is always to want more. Hashem created man and tested this theory. Adam and Eve, psychologically speaking, were underdeveloped. They couldn't reason, "I have access to % 99.999999 of the universe, and I'm in Paradise. I should be happy." They wanted EVERYTHING. So they ate from the tree. Despite Hashem punishing them for the sin, we see Abraham, Isaac, and Jacob were blessed with pretty much everything, as was King Solomon among others in Tanach and Jewish History. They were on a different level than Adam and Eve. But Hashem used Adam and Eve to teach us the value of life. To not only be happy with what you have, but to prove that despite human nature to always want more, we must look at what Hashem has given us, and always appreciate it.