Sorry to be frank but you have it totally backwards. Converting HBD to Hive would break the peg even more, by reducing supply of HBD when demand is so high. It would also make a loss for everyone who does it. The supply of @hive.fund also doesn't count towards the debt limit.

I don't get all the economics of this, but it seem we are not gaining much from having HBD generally.

1.7 million Hive was removed from supply in the last 24 hours. That is not "we are not gaining much". That is equivalent to an enormous dividend for investors. It is the reason Hive is being stripped from exchanges and the price is rising.