If any of you are wondering what maniac would lock up HBD for 30 years, you have to zoom out a bit to get the full picture. 

First, you can buy and sell bonds. 
https://www.finra.org/investors/learn-to-invest/types-investments/bonds/buying-and-selling-bonds

Second, the reason you are doing this is to package HBD into large units. When you borrow from the bank, you pay a premium for every dollar you borrow. For example, I'll buy $1 for $1.10. Or, like a 30 year mortgage, you are buying $100,000 for $200,000, effectively. Buying and selling individual HBDs is inefficient. You can pack them up in units of 1000 HBD to buy and sell. Why buy bonds? They pay interest in guaranteed amounts. 

In the case of HIVE, we would collectively be buying money to be locked up in HBD, which would reduce the amount of HIVE in circulation, thus raising the value of HIVE. In order to make all this happen, the HIVE blockchain would incentivize savers with interest payments. This is similar to corporate bonds, which companies use to borrow money. You may think that stocks give you ownership of a company. However, bonds have to be paid first. Stocks get whatever profit is left over, if anything is left over. Bonds are a direct claim on capital. 

In other words, with bonds, all of us Hivers would be buying money to lock up in our blockchain for 10, 20, 30 years. We would simultaneously be the lenders and borrowers. And, as bonds would be hard-coded into the blockchain, they are guaranteed income that is tradeable. This long-term stability is what could make HBD a less volatile stablecoin as we would have a constant release and lock up of HBD as bonds mature and are issued every month. 

In other words, bonds would be like miner tokens for HBD.