User blog comment:B214/High School DxD BorN Episode 9 Review/@comment-23847729-20150601192532/@comment-26322543-20150602032630

All of the past possessors (minus Elsha and Belzard) were said to have died drowning in their own power, which left their grudge and regret in the BG. So it's probably more that they only cared about killing the Hakuryuukou and threw their lives away using JD. Same for the past possessors of DD.