OpenAI's Stargate project to consume up to 40% of global DRAM output (tomshardware.com)

This is the type of hard constraint that could seriously hamper scaling. You simply can't scale hardware at this level without some supply chains issues that increase costs enormously. Similarly with electricity production.

Story from October 1st;

OpenAI post: https://openai.com/index/samsung-and-sk-join-stargate/