Only works so long as you eventually pay up... well unless the manufacturers make too much this way. That said are there some Chinese manufacturers that aren't part of the cabal and could undercut them?

Except that it doesn't work like that. If you buy DRAM and don't do anything genuinely worthwhile with it, you'll ultimately dump it all right back onto the market, and everyone knows that. The biggest worry is that it's actually OpenAI and their direct competition starving the rest of the market because they predict AI research and the like to be a highly valued use for the stuff, compared to building gaming PC battlestations or whatever the highest-valued use was before. Many observers think that this will also happen with GPUs and cutting-edge digital logic more generally.