Parsha Shemot offers an account of how Bnai Yisrael went from free men in Egypt to slaves to pharaoh. Just about every commentary I see views the Egyptian reaction as based on paranoia. Rabbi Barry Leff speaks for the overwhelming majority when he says pharaoh was the world's first anti-Semite. The Egyptians were the first people to persecute the Jews as a people.
Let me offer some contrarian comments. I think there is a reason behind the Egyptian elite's decision to enslave the Jews, the Jews' passive acceptance of the initial stages of enslavement, and the Egyptian populace's total lack of sympathy for the Jews' enslavement.
That reason is Joseph, and his behavior after the famine began in Egypt. As you will recall from Vayigash, Joseph reduced the populace of Egypt (except for the priests) first to penury, then to outright slavery. He was able to do this by selling the Egyptians the food that he had taxed away during the seven good years - food that he had stored in such abundance that he could feed not only Egypt, but many people from Canaan as well.
Having reduced them to slavery, he then imposed mass population transfer in order that the Egyptian people would be uprooted. No one could say 'my father owned this land, and my grandfather before him'. He essentially exiled the people of Egypt within the borders of their own country.
This seemingly left Bnei Yisrael as the only other free group within the land of Egypt. What could be more reasonable to the Egyptians that they feared that the Jews would misuse freedoms that the native Egyptians were deprived of? What could be more reasonable than for Bnei Yisrael, when asked to volunteer their labor, to accept? After all, everyone around them were slaves - demanding that they perform labor for the government as well no doubt seemed reasonable.
And lastly, while perhaps the Pharaoh 'knew not Joseph' I would not be surprised if the Egyptian commoners remembered perfectly well who was behind their present situation. Schadenfreude at the Jews' troubles seems a nigh inevitable reaction.