bHBD and HBD were swapped 1:1 so leo finance received 1 HBD for every bHBD you wrapped. Therefore no matter the price 1 BHBD = 1 HBD.

Working on your theory of paying back only what someone paid for bHBD on BSC is ridiculous. If you pay someone 50 cents for 1 bHBD then Leo finance makes 50 cents.
Not sure what you don't understand about wrapped and unwrapped tokens having the same value

Just explain why 1 bHBD doesn't equal 1 BHD