The reason it went to $8 is because the exchange Upbit listed Steem/SBD and people who didn't know anything about Steem bought SBD which is suppose to be a pegged asset, when they did they started to raise the price and then others who didn't know what SBD bought due to FOMO and it just snowballed.

There was also only around 1M SBD at the time and we have far far more. It was a perfect storm of luck and ignorance that will never likely happen again.