In addition to what queermunist said, the US is an ideologically capitalist country. It is unwilling to do things that may seem socialist even if the benefits are clear. And only a state-owned or state-backed enterprise would be willing to pour in decades of investment (read: net loss) before they are in a position to sell their products.
Also, China can partially or completely drop export controls at any time. And most civilian industrial users of rare earths are Chinese companies. (The civilian market is much bigger than the military one.) Chinese factories are more automated and have shorter supply chains, and so would be able to sell their rare earths cheaper than US ones. So a Western company would be risking not even getting a payout at the end of these decades of investment.
In addition to what queermunist said, the US is an ideologically capitalist country. It is unwilling to do things that may seem socialist even if the benefits are clear. And only a state-owned or state-backed enterprise would be willing to pour in decades of investment (read: net loss) before they are in a position to sell their products.
Also, China can partially or completely drop export controls at any time. And most civilian industrial users of rare earths are Chinese companies. (The civilian market is much bigger than the military one.) Chinese factories are more automated and have shorter supply chains, and so would be able to sell their rare earths cheaper than US ones. So a Western company would be risking not even getting a payout at the end of these decades of investment.