Maybe he just wants some rest for his soul but all these danderblasted humans keep reviving him. You'd be pissed off at humans too if they kept waking you up.
Sounds like Vincent from FFVII.
I'm going to agree with Archangel. From SotN on, he's been less "vengeance for your hypocrisy, murdering an innocent under the pretense of innocence" and more "enslave and slaughter all who oppose me." Methinks it may be a tad more complicated than him simply being devestated and drawn to incite utter chaos.
I'm going to expand a bit on what's already been suggested, and say that once he heard from Al Lisa's last wish, he underwent a total mental breakdown in between his SotN death and his next resurrection. Giving that he knew Lisa and her personality well, seeing as he was deeply in love with her, etc., I would imagine that he had some manner of festering thought that her final wishes were of the forgiving nature. Maybe he had always had some lingering feeling that he was doing everything for naught, but that thought made him realize that he was betraying Lisa and damning her loving nature as her murderers had. With such a horrible and definitely plausible notion in his head, I'd imagine it was either easier for him to continue his conquest against humanity, OR that he blamed them further, for not only killing Lisa in the first place, but also because of that leading him to the unpleasant mindset of his futility, and killed them under that pretense.
Or, since he and Castlevania take on a new appearance with each incarnation, certain memories linger and others fade. Obviously his anger is strong enough to carry on, but he makes no real mention of Al, Lisa, specific Belmonts, in future games. He makes, if I recall correctly, obscure references to them. He, in DXC, says "Belmont, son of Belmont," possibly indicating that he knows the aura of the bloodline, but cannot remember any past incarnations well enough to directly recall them. Or he can, and just chooses not to. In any case, the possibility I'm suggesting is that he retains and loses certain thoughts, memories, grievances, etc., with each death and revival he goes through.
This is a really interesting topic. Good call in putting it up, Archangel.