Why does dark star thresh say thank you when he's killed?

He is entropy incarnate. He wants to destroy everything or see everything's destruction (or both), even it includes himself. He wants to put everything in eternal sleep, absolute oblivion.

well think about it... you know thresh an immort being... dark star where he is just an endlife life of destruction... your freeing him. Its like he doesnt want to die so he fights to live but he is not sad about dying because then he is finally free

"Ha, thanks Bro. I wanted to shop anyways. Thanks idiot."