This is what I would bet on. If you spent decades of your life knapping various "easy" and ideal stones for tools and getting quite skilled at it, it doesn't seem like much of a stretch for them to try knapping a "difficult" stone just because it looks cooler and you can show it off.

Exactly. Same reason kids and people today are drawn to it and gems in general. Even today, people imbue crystals with mystical properties.