Another reason why Dovid was so against Doeg, since: דְאָּגָּה (worry) is the opposite of Bitachon and Sameach B'chelko. The Gr"a says that the true Shoresh (root) of Sin'as Chinam (which caused Churban Bayis Sheni) is lack of Bitachon, i.e., not being Sameach B'chelko. Indeed, Doeg personally killed the entire Nov Ir HaCohanim, and that was the end of the Mishkan that rested in Nov. It is truly fitting that Doeg דְאָּגָּה (worry) is the destruction of the Mishkan (just like it destroyed the Bais Hamikdash).
And Dovid’s entire: מְ צִ יאוּת essence was Bitachon and Sameach B'chelko, which is the Kiyum and basis of the Bais Hamikdash, and Doeg is the Churban. So Doeg is the extreme opposite of Dovid and all he stands for. P.S. The very best people in the universe are the “worriers” who WANT and TRY to be Sameach B'chelko.
