Actually we know exactly why hive is moving off exchanges. It's not even moving off exchanges, it's moving off the planet.
Hive is being converted to HBD, so it just disappears from the supply. They're not in wallets anywhere. Check out @penguinpablo's daily report for conversion stats.
ya saw that, really nice to see. HBD can be a strong driving force for Hive, esp in e-commerce