That perspective is a little wrong; those are the 4 companies on the edge of a wave of technological improvement. It isn't unusual for there to be unique companies in those circumstances. For example when Apple hit the market with the iPhone back in '07 there were similar things going on. One of the things that hamstrung Apple's competitors was that nobody in the supply could manufacture equivalent parts.

Those 4 companies aren't without competitors. But if you pick the best in each category there is (funnily enough) only one option and right now chaining them together gets a noticeably better product than anyone else can build. That isn't normal but it also isn't that weird for new products.

If you want what Nvidia was building a few years ago there are several of options.