Why are people not investing in this?, page-42

You are right. They could become a 'substantial or majority holder'. I don't have any more specific knowledge about the subject but there may be policies at GM that would guide/govern this type of decision.

I was not implying they would actually do the X+Y for Z thing exactly. Just the general point that successful businesses often limit themselves to their core knowledge, and buy everything else as needed. On the other hand, in this situation they reduce their risk by not taking a position in CXZ but increase the risk by leaving this product at the sole discretion of one small company. Which adds weight to your original point.

I have sometimes wondered why Tesla don't just buy out enough Lithium mine's to meet their future demands, while they are still relatively underpriced. Elon seems capable of succeeding in anything he puts his mind to but maybe his latest Battery day comments suggest he has reached the limit of his knowledge in that field (I am being facetious - I know he had a vested interest in saying what he did)!

I believe there are enough examples of big businesses that tried to control and own everything within their orbit, and that still did not work. There has to be a limit somewhere I guess.