At the time of the exodus from Egypt, the Jewish people did not go out empty-handed, like so many slaves fleeing their masters. The Egyptians bestowed great wealth on their former slaves as "going away presents." Indeed, so had G-d promised their forebear, Abraham, four hundred years previously:
And He said unto Abram: 'Know of a surety that thy seed shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years; and also that nation, whom they shall serve, will I judge; and afterward shall they come out with great substance.
At that time, Egypt was the leading world power, in a position similar to that of the United States today. It was the last word in culture, and had accumulated immense wealth. Many of the enormous structures that brought it fame and stature among the nations of the globe, still draw millions of tourists yet in our times.
Suddenly it became clear to the Egyptians that the vast wealth they had amassed over years and years had fallen to the hands of the former slaves, the Jews.
After the exodus, Jethro, the father-in-law of Moses, our teacher, came to visit the Jewish encampment in the desert. He asked to hear about all the miracles that had befallen the Jewish people when they were redeemed from Egypt; he was eager to understand just what had transpired. Moshe replied with an answer that conveyed the most fundamental understanding:
And Moses told his father-in-law all that the L-rd had done unto Pharaoh and to the Egyptians for Israel's sake, all the travail that had come upon them by the way, and how the L-rd delivered them.
Everything that G-d had done to Pharaoh and to Egypt is described as having only one purpose; it was all "for Israel's sake." The rivers that turned to blood, the crops that were consumed by locusts, the plague that decimated the country's animal resources, the death of the first born throughout the country – it all happened for the benefit of the people of Israel.
The wheels of history do not move by themselves. Nor do they move without reason. The Creator makes them rotate, and He has clearly defined goals in mind, which He described in His Torah.
Directly or indirectly, everything that takes place is intended by Heaven to bring Israel that much closer to achieving its ultimate goal in the service of the Creator. This is one of the basic lessons of the Passover holiday.