Andrew hussie wanted to expand what dirk could become, his story was definitely not over by the end of homestuck and we see that in the epilogues, the epilogues are despicable and gross as hell.
The way andrew hussie completely wrote dirk's character makes me believe he wanted to allow us to see the mindset of a fucked up abuser, wanted to completely destroy dirk strider, which props to hussie, I love destroying my ocs
Making a character with super awful flaws is like really interesting and the fact that dirk strider completely destroys himself is exactly what a prince is, it's always been an inevitable with him