Staking LEO only earns you curation reward by giving you a more powerful upvote which you get 50% of.
HBD can be used on some applications as payment for things such as NFTs or tokens. Or you can go to the internal market and swap them for HIVE then power that up. The internal market is in your hive.blow wallet.
Or you can use swap.app to convert them. Simply sent the HBD to @swap.app and it will return you the appropriate HIVE in a less than a minute.
RE: Am I stupid, or what? Can't fully understand LeoFinance mechanisms