OK, serious thoujght. Reflective glitter would make one hell of a paint additive for roadway and other markings. I do remember there was a shortage of reflective paint a couple years back, because China was using so much of it. Not sure on this since mica is probably used in both products.
And on a more somber note, the metallic pigments used in glitter are derived from the mineral mica, a great quantity of which is mined by up to 22,000 child laborers in India alone, which exports 25% of the world supply (the other suppliers being Brazil, China, Pakistan, Peru, Sri Lanka and Sudan). The children are as young as six years old. Besides working in harsh conditions, they contract asthma, silicosis (an often fatal lung condition), and TB. Mica is also used in paints, consumer tech, and makeup.
If you look, there are mica-free makeups and glitter.