The entire nation—Jeremiah is reporting here on Judah, just because Nebuchadnezzar invaded in 607 BC—was spiritually and morally sick. This statement, "and the priests rule by their own power," means, in more modern language, that the priests were functioning by their own authority—that is, they pushed the law of God aside.
The people loved it because in so doing, they allowed themselves to be deceived into thinking that the restraints and penalties of God's law would not affect them. "It won't happen to me." How do I know that? Because that is what God showed happened in the Garden of Eden. "You shall not surely die." Adam and Eve became convinced that it was not going to affect them if they disobeyed what God said. "It won't really affect me." They fell for what Satan sold them on.
