As with every word definition these days, it is actually the opposite. Same with “rare” earth minerals. They aren’t rare.
They are rare in the sense there aren’t large deposits easily extracted, at least not in the US. Aerospace applications use a lot of titanium and exotic alloys. Back when the government actually thought of such things, they maintained stockpiles of them for national security reasons. Importing exotic minerals from far flung places like the Congo meant America was subject to disruption, in a similar way to Rubber from Malaya during World War 2, the Japanese cutoff the supply almost completely.
Americans were prohibited from possessing more than five (5) tires, a national 35 mph speed limit, and gasoline rationing imposed, primarily to save tire wear.