The plagues are not only punishment. They are curriculum.
The Targum Pseudo-Jonathan on Exodus 10:2 records the Holy One's own reason: "In the hearing of thy sons and of thy children's children may be told the wonders I have done in Mizraim, and the signs that I set among them, that ye may know that I am the Lord."
The Aramaic paraphrase, preserved in the Targum long attributed to Yonatan ben Uzziel, is precise about the audience. Not just the generation leaving Egypt. B'nach u'bnei b'nach — your children and your children's children. The plagues are being staged for a conversation that has not happened yet, between a grandparent and a grandchild in a distant century.
This is the theological origin of the Pesach Seder. The Haggadah is built on this verse. Every year, for over two thousand years, Jewish families have sat at a table and obeyed this instruction: tell the children. Show them the signs. Pass the memory forward.
The Maggid teaches: the Exodus was not only a rescue. It was a transmission. The Holy One wanted a story that would still be told when the Egyptian empire was dust — and it is. Pharaoh's dynasty is a ruin. Israel's Seder table is still set every spring. That is the ratio of power the Targum is pointing at. A story outlives an empire.