Some people think this is because Microsoft does not know what Bitcoin is or what they are doing.  I would say this is almost impossible at this point.

Microsoft used to ACCEPT Bitcoin at a particular stage many years ago.  They surely do know what Bitcoin is and how it works and I highly doubt they do not know about it being a great Investment opportunity.

However.  What they do and say publicly does not equal in reality their exact set of mind.  They are likely not putting any Money into Bitcoin because it does not benefit them, their image or their Corporation in any way.