Man has an innate desire to see the fruit of his own efforts. When life's blessings are handed to one on a silver platter, those blessings are robbed of much of their meaning. This explains the well-known phenomenon in which children of very successful parents want to strike out on their own, gaining their own sense of accomplishment. Though their success can often be attributed to the support and the safety net of successful parents, nonetheless, these children feel that they have succeeded on their own.
In a similar vein, G-d's kindness manifests itself by allowing man to feel that his successes are primarily due to his own hard work, and not because of G-d's benevolence. We would find it difficult to enjoy our success if G-d's role was too overt; only through our own hard work can we feel the joy of our success. Thus, the farmer, after labouring so intensely to produce fruit, can "rejoice in all the good that G-d, your Lord, has granted you and your family" (26:8).
It is all too easy to fall prey to the other extreme, namely, feeling that our entire success is due to our own efforts. That same farmer must bring his fruit to the Temple and publicly acknowledge G-d's ongoing role in history, thereby admitting that his efforts would have been fruitless without the blessings of G-d. No one knows this better than the farmer, who understands that one bad storm can ruin six months of hard work.
While the farmer has no choice, and must put in the work without knowing what the result will be, the fear of wasted effort often prevents people from attempting to achieve great heights, especially in communal affairs. Why expend all that energy when success is far from certain?
While seeing one's efforts go for naught is a most distressing experience, it is far worse to see others expropriate your efforts for their own personal gain. For this reason, Jewish law forbids a departing employee to actively court the clients of his former firm; to do so would be to take unfair advantage of the firm's efforts in recruiting that client in the first place.
Yet such wasted effort, and the expropriation by others of our hard work, is the fate that awaits the Jewish people if they ignore the warnings of the Torah.
"When you betroth a woman, another man will sleep with her. When you build a house, you will not live in it. When you plant a vineyard, you will not enjoy its fruit. You ox will be slaughtered before your eyes, but you will not eat from it...your sheep will be given to your enemies, and no one will come to your aid. A strange nation will consume the fruit of your land and all your toil. You will be constantly cheated and crushed" (28:30-33).
The impact of working so hard for naught, or worse yet, so others can take advantage of you is such that immediately thereafter, the Torah tells us, "You will go insane ( meshugah ) from what you will have to witness" (28:34).
Moshe Rabbeinu, over and over again, demonstrated his willingness to suffer so that the Jewish people could prosper. It is this point, I believe, that is key in understanding why Moshe was the greatest leader in history. While we may not have a Moshe Rabbeinu to lead us, let us strive to maximize our efforts for the benefit of the Jewish people and mankind in general. We can trust that G-d, in His infinite wisdom, will ensure that our efforts will be rewarded; and that someone, even if it's not us, will reap those benefits.
It takes a great person to lay the groundwork for something from which he will never benefit himself. This helps explain the short-sightedness of many politicians, business leaders, and the like, who focus on extending their own terms in office, often sacrificing long-term interests for short-term gains that benefit them. The financial crisis threatening the world economy is a prime example of this all-too-human failing.