From a standard exploration / production boom / bust mineral resource supply / demand PoV this is commonplace forward looking anticipation being weighed against the upfront capital costs of processing infrastructure investment.

https://www.iluka.com/products-markets/rare-earth-products/

Not sure about Lynas and whether they have access to those rare earths from an alternate source to feed into their plant. The Mt Weld mine is carbonatite and mostly LRE rather than the Yytrium and Erbium heavy xenotime/monazite Iluka have stockpiled.

But then again I certainly wouldn't want to be the youth of today and expect the same outcome.