Perhaps, but there are other ameliorating factors. First, I believe this all happened when Apple was still licensing hardware (to PowerComputing, etc.). Second, there are a number of people, I believe, that would want the additional support Apple would be likely to provide for running on an approved system. Third, I think a significant number of people would like to have a reasonable, supported alternative to Windows. And fourth, once that OS had become moderately successful for a period of time, hardware upgrades could become cross-upgrades. I don't think it would have been too difficult to develop a binary compatibilty layer (probably embedded in the OS's API) so that all (or most) applications could run on either architecture.

You may be right, anyway, but I've always thought that there was something there, even if it ended up being self-serving on Apple's part. Mr. Gates is not really known for his generosity, certainly not in business situations, and I can come up with little other reason for that investment. I doubt that sales of Office for Mac are keeping Microsoft afloat.