Satan progressed greatly in intelligence in premortality, perhaps to the point that he thought that Godhood could be achieved almost exclusively through the academic exercise of pre-existence. Once we've accomplished our certificate of completion, he may have thought, our Heavenly Parents would just give us our bodies and their glory, and we'll move on into Godhood.
But it's not that way. Our Heavenly Parents didn't become Gods that way, and one can't become a God simply through intellectual exercise. Eternal law dictates that physical experience must be involved.
Satan thwarted in the Garden of Eden the exact type of plan that he had recommended--in order to put in motion the exact plan that he opposed--in premortality. Perhaps he did it because it would be, in his eyes, the quickest way to show what a failure God's plan would be (even though that was the same plan that had been followed with relative success in other worlds that had come before).
The Parables of the Prodigal Son and the Laborers in the Vineyard must be taken together, because looking at them separately can lead one to improper conclusions about the magnificent reach of the atonement.
The Prodigal Son, although he repented, returned, and eventually inherited alongside his brother all that his father had, took great risk by turning to riotous living that he would never want to return to his father and his inheritance. The risk in sin is not that it can't be cleansed by the atonement (because pretty much every sin can), but rather that we won't want our sins cleansed by Christ because we have become comfortable with them and they have become an integral part of who we are--that we don't want to give them up. (See Mormon 9:4, Alma 12:14)
In the timeboundness of mortality, it's easy to see and think that we forgo opportunities and blessings when we sin--and it's probably healthy to think that way--but in the timelessness of postmortality, does that even matter? The atonement of Christ can justify us (declare us innocent of previous wrongdoing) and sanctify us (purify us from a future desire to do to wrong). That is the essence of the parable of the Laborers in the Vineyard is that it doesn't matter when you repent--you are just as cleansed by the atonement in the endlessness of eternity as anyone else.
Because of this, the gospel of Christ is the epitome of grace. It doesn't just apply to Mormons. It doesn't just apply to Christians. It applies to everyone who ever lived, even if they never get a chance to learn of Christ and his gospel in this life. Because every one of them knew intimately of Christ and his gospel in their previous life--and they supported Christ as part of our Heavenly Parents' plan. And the vast majority of God's children live lives of kindness and honor.
Life is all about relationships. Similar to the relationship-destroying, short-circuiting "get rich quick" schemes that we sometimes succumb to in this life (which take all the fun out of the experience of the journey anyway), Satan seemed to have his own get-rich-quick scheme in premortality. We'll do all the learning, he seemed to think, and our Heavenly Parents will then say "Presto! You're all gods now." But that misses the entire point of life--other people and the relationships with them. The trials and struggles that we go through with them in mortality.
The entire point of the concept of "self-reliance" in Mormonism is not to become some individualist like Ayn Rand on steroids, who cares about no one but themselves, but to become exactly the opposite. When we become truly self-reliant we become outward looking. We improve our lot in life to the point where we are capable of helping the downtrodden improve their lot as well. And if we happen to be one of the downtrodden at various points in our lives, the self-reliant and outward-looking acts of others toward us are sure to motivate us to "pay it forward" when we arrive at a point that we can do so.
But I don't think Satan understood this. To him, I think, it eventually came to be all about achievement and competition. Satan very likely initially felt he had everyone's best interest at heart when he brought his mortality-bypassing plan to the Grand Council in Heaven (Doctrine and Covenants 29:36). It says in the scriptures that Satan wanted God's glory for his great idea, but I think we often get the wrong impression of what he initially wanted. I think he wanted everyone's glory by not requiring us to pass thru the vicissitudes of mortality and achieving godhood the easy way (which actually is not possible). But then when Mom and Dad said, 'Son that won't work', he became angry and sought to prove his plan valid by destroying the one presented by our Heavenly Parents, the one that had been tried successfully in other worlds so many times before, and the one that all of us who made it to earth supported to one degree of passion or another.
BUt while Satan turned out to be an "all about me" guy, Christ understood the intricate value of everyone else around him. When he speaks in Isaiah 50:4 saying "the Lord God hath given me the tongue of the learned, that I should know how to speak a word in season to him that is weary", it shows clearly the value he placed on those relationships with us.