Even the iPod was entering an already established market (consider the Sony Walkman).

Although that is interesting… I found some stats and 385 million walkmans were sold over 30 years. About 10. Million per year. Another report claims 51 million VR headsets in the last 5 years or about 10 million per year… (I started this comment planing to be negative, but now I wonder if Apple is not hitting the market at just the right time…)