The iPad has an installed base of over 300 million. This is a far larger audience than that of the Mac (which has somewhere between 100 million and 150 million). And whereas the iPad acquired this audience in about 7 years, the Mac took 33 years.Curiously however, it is the iPad that is seen as the more fragile product. The iPad is considered to be failing, with a presumption of an end of life in the near future. The evidence of this failure the year-on-year decline in units sold. This is illustrated by the following graph.  Note that the iPad decline is paired with...