Honestly, it makes perfect sense to me, but that’s probably because I have astigmatism.

We’ve seen the head as the seat of intellect for millennia, and glowing things (the sun, moon, and stars) have always been endowed with mystical and miraculous properties.

Glowing things look like pointy rings if you squint or have impaired vision. Combine those simple concepts – pointy glowing wreath on the head – and you get a crown.

(And earlier renditions were just gold wreaths, often made of leaves, like the Roman laurels.)