If pages are served their aspect, or serve themselves selfishly, then why did Grandpa "serve" humanity sburb ? What's your opinion on it ?

Like most stuff with the Passive/Active Dichotomy, things flip from one side to the other from times, so Grandpa serving SBURB to the world is fitting thematically. That being said, in doing so, he’s also basically dooming all of Humanity to a meteoric death in the first place, even if it was predestined. It’s a bit difficult to say, what is selfish, what is selfless, what his intention was, because Grandpa is a weird individual. Specially because, also? That’s ASSUMING it was his idea to spread it around. Remember, Grandpa is dead by the time Homestuck starts, by several years. For all we know, he was only studying the code before dying, and then someone took up on the task to finish SBURB and spread it.