I have seen answers about putting fear in them, saying things like you are losing rewards if you don't power up. I agree that this would make them sell. I would rather say: People are saying a decentralized social media is the next big thing, HIVE is positioned to be the platform that achieves it, invest early and earn some passive income(powering up) in the process as well.
Most people don't know what the token they are holding is about. Make them see the macroeconomic aspect of hive rather than the microeconomics of it.
Hive strenght relies in that message, not in the %yield. Don't even try to attract them with the potential yield they can earn, for that they have DeFi.