It's easy. Any meaningful picture contains many points - pixels, if you like. So one point (pixel) is not sufficient to describe the picture of a complex thing. But we may construct this picture point by point, OK? Each point belongs to the whole picture but is insufficient to represent it. Now, the wave function squared is the whole picture and each separate, elementary quantum mechanical "measurement" is a pixel of the whole picture. The wave function does not collapse while measurement. On the contrary, each "elementary" measurement is the information bit retrieval, if you like, necessary for description of a complex thing.