It takes double digit billions to start a manufacturing plant and that's when you already have people who know what to do.

Most countries can't really afford this in their budgets and I'm saying countries because it'd be a stupid endeavour for most private enterprises to even attempt. CXMT (DRAM) and YMTC (NAND) absolutely are sponsored by China, which is the only real way to get one of those companies going these days.

Google, Apple, etc could start their own memory companies if they wanted to. But it's a hell of an expense to justify to your investors.