By design it is supposed to gradually lose value if the amount of HBD in circulation exceeds the limit of 20-30% of total Hive market cap (currently 6%). In practice it may do better because some may get converted away as the limit gets closer. It is also possible (if not necessarily likely) that speculation could keep the market price up even as the algorithmic backing declines above that "haircut limit". But no one should depend on either of these happening. If you buy HBD you are risking a haircut under highly stressed market conditions. Nothing is truly "risk free". At least HBD is transparent about these risks, other algorithmic stable coins may not be. But they all have risks.