I think I have something to assist you in understanding SBD more. The availability of SBD on external exchanges means that it is part of a free market where supply and demand factors in. Price can fluctuate due to many reasons and so it did.
The option is not available in the wallet at the moment but there use to be a CONVERSION option from SBD to Steem.
When the peg was broken, the conversion feature was removed perhaps. One of the reasons the peg broke was that the SBD/Steem conversion was just one way. Had it been two way, users would have been able to convert Steem to SBD when Steem value was high and convert back to (more) Steem when the value was low. SBD would have stayed inside the blockchain in such a case and the price could not be manipulated on the external exchanges.
The recent discussion around pegging involves suggestions to implement two way conversion too. Let's see.
One of the most effective determinent of SBD generation is value of the votes. How vote value is calculated may be a bit complex but at least 37.5 % of all the votes that happen on the blockchain result in SBD (0.375 SBD from a $1 vote). That's a major consideration in knowing how SBDs are generated.
The factors that affect vote value affect SBD generation as well. I hope it adds to your knowledge around SBD and vote value.
Thank you very much, this is an extremely useful link which demystifies (in a positive sense) further the steem blockchain. As an IT architect, I now begin to understand the main entities in the steem data model - especially the interpaly between the "reward_balance" pool and the "recent_claims". very, very useful, kudos !