Why was it hard for peapole to accept a helioetric concept of the solar system

Because the theory of Heliocentrism is contrary to the theory of Geocentrism which places the Sun as the center of the solar system. In contemporary science, we can know that the sun is the core or axis of the Milky Way galaxy. And there are many other galaxies that are millions of light-years away from the Milky Way.