Indeed. Rare earths are specific elements in the periodic table. The only way we could "synthesize" these elements is atomically -- by bombarding other elements with nucleons and hope they stick or split. "Not economically worthwhile" is a massive understatement. :)

A similar process is required to turn lead into gold!

Well rare earth elements are heavy metals, and so it's about their atoms that is important. It's not something you can make via chemical processes, you'd need some kind of nuclear process, like how new atoms are made (kind of like how scientists make synthetic elements with more than 92 protons). Either that or split a heavier larger atom into the metals you want, although this means it would in either case be unstable.

The amount of energy to do these is so incomparably huge to just digging them out of the ground.

The necessary transmutation simply requires the philosopher's stone.

Unfortunately, I seem to have misplaced mine...

More of a meta comment, but it's not appropriate to downvote someone for asking a question in honesty, even if "everybody should know that ___".

(parent: this isn't meant for you, more at whomever downvoted you)

The main value of the minerals is in the rare-earth elements they contain. If you already had access to those elements in a different form, synthesizing the minerals is of little value. (And of course nuclear synthesis of the rare-earth elements, to the extent it's possible, is very very far from being economically viable.)

Rare-earth elements are formed in supernovae, so if you happen to have a supernova in your backyard, you’re golden! Otherwise, it’s a rather expensive ordeal, battling those subnuclear forces.