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However, this leads me to think that having 7% interest on a stablecoin is potentially a big win for Hive. I wish I understood where the 7% comes from. If it's newly minted Hive, then that's just as bad as the Federal Reserve. However, if that 7% comes from the Hive reward pool, I can see that as beneficial to the Hive community. But, that's just my uninformed opinion.
The reason I think the 7% interest is a big win is that it can attract outside capital to deposit on the Hive blockchain. If you have HBD on an exchange earning nothing, or HBD on Hive earning 7%, the choice seems simple enough. A 3-day withdrawal period doesn't seem too bad. But, if you're sitting on TUSD, USDC, or USDT earning under 7%, you might look at HBD.
Onramps
I did look at @Blocktrades. You can't directly convert from USDT or USDC into HBD. But, you do have other options to transfer your crypto into HBD, such as BTC, LTC, Dash, ETH, Monero, and BCH. I haven't looked at what options Hive Engine has. However, I am sure that there are more options that would require an intermediate conversion to SWAP.HIVE before you can convert to HBD. The point is that there are onramps for value to flow into the Hive blockchain for it to serve as a bank of sorts.
Security
The same protections that make Hive safu from another Justin Sun event are the same protections that would protect the value of HBD depositors on the Hive blockchain. And, the greater the value of the Hive blockchain, the more expensive, thus more difficult, it becomes for anybody to try to take control of the top witnesses.
Retention
The biggest win, in my opinion, is that earning interest on HBD savings means that more of us Hivers will choose to keep our HBD on-chain. Perhaps we may even be persuaded to deposit our savings into the First Bank of Hive.
When HBD is Abundant
So what happens when HBD is abundant in our wallets? Can we use the stablecoin to book trips on Travala? Will we be able to use it for commerce? We are already able to lend out HP. It might be interesting to be able to collateralize Hive to borrow HBD.
Of course, all of this is dependent on whether a 7% return is sustainable. I still don't understand where the 7% comes from. I do understand that the rate could go up or down if the witnesses agree on a number. But, if the 7% results in increasing deposits from non-Hivers, we potentially may see Hive become something totally different from what we have seen in the past. The witnesses would have no incentive to lower the rate. Would Hivers prefer to convert their Hive to HBD than power it up? Who knows? We all have different financial ideas and circumstances. Hive has increasingly implemented changes that give us more choices on what we can do with our earnings. At the same time, we increasingly have less incentive to take our earnings anywhere else.