They sold software tools at the beginning and further down the line used the tools to become the platform of choice for corporations. They controlled the OS and

They sold software tools at the beginning and further down the line used the tools to become the platform of choice for corporations. They controlled the OS and the tooling and this gave them great advantage in business software market share. You could get Windows source (or parts of it) if you needed to work on low-level stuff from MS and their MSDN was and is miles better than Apple developer documentation and tooling.