Interesting thoughts - especially for a relatively new HBD user such as myself
I did have quite some considerations before starting a HBD savings account. Not necessarily because it felt unsustainable but more because it affects all hive investment / gaming projects.
Being a financial geek - i try to do scenario analysis on all my potential investments before I join in - using the discounted cash flow method both to create a forecast of expected returns aswell as correcting the investment for opportunity costs by using the 20% interest from HBD as the discount rate. This high yielding and relatively lower risk alternative makes it hard for new projects to end up as attractive. Having such a high opportunity yield might prevent funding to solid projects (or force them to make more risky decisions) and thereby slow down innovation.
Smart.