RAM production is historically not a great business to be in. It’s a mint today, but it’s an incredibly tough business to break into & by the time any hypothetical Apple RAM fab is up & running, it will already be losing money.
To give you some idea, here’s an Asianometry video describing Taiwan’s prior DRAM attempts: https://youtu.be/ehT3U935Pww
To give you some idea, here’s an Asianometry video describing Taiwan’s prior DRAM attempts: https://youtu.be/ehT3U935Pww