Yes, you are correct when the price of SBD is high.

However, when the price of SBD is close to or at $1.00, then it can be used a "hedge". In a bear market when prices are going down, SBD can be somewhat of a safe place to store value as the bottom of SBD price is fixed at $1.00

I would like to point out that there is risk. The risk is if STEEM price goes too low, then it cannot support the SBD peg. There is a mechanism that is called a "hair cut" that helps prevent STEEM from going to that point. The hair cut would allow SBD to drop. From what I have read, the "hair cut" has never been implemented.