In the late 70's and early 80's microprocessor technology was becoming advanced enough to finally leave the realm of hobbyist computing and become a commercially viable commodity market. Apple was the largest manufacturer of personal computers. If anyone had an advantage in that market and was in a position to ride the revolution it was them. Now 35 years later Microsoft Windows is the dominant operating system in across both business and home computer segments.
The only explanation for how this came to pass that I've seen that you won't argue with is "They're all stupid".
I recall clearly when the decision was made by my then employer(a big high tech company) to dump Apple for the new IBM system. It was an extensive process and the Apple products came out lacking for the business environ. Guess they were just all stupid. I think they are still called intel. Oh and the operating mainframes were HP not IBM.