Why does precipitate always form so naturally? Whether be it from a textbook or teacher, precipitation reactions always occur by rearranging the elements:

For example


But then, aren't there other factors you have to bare in mind when predicting such reactions? Like electronegativity: obviously the potassium ion is much more electronegative than Silver ion, so it wouldn't be that easy for potassium to split up with iodine.
The ions combine while in solution, and since the resulting compound is not soluble, it precipitates. This happens so quickly because as the precipitate forms, it takes those individual ions out of solution, thus pulling the reaction toward the products side, according to Le Chatelier's principle.