Why is saffron the most expensive spice in the world?

Saffron harvesting process and its distinct quality smell,
and color make it the most expensive spice.
. For single kilogram of Saffron can cost you up to $4000 or
above.
. Harvesting saffron needs a lot of labor, you would need
to pick 85,000 flowers to create one kilogram of saffron.
. There’s also a specific time period in the day to harvest it.
. Saffron is most commonly used in kitchen, a signature
dish is paella.