Why does Horatio keep asking the Ghost to speak?

Horatio is the one who challenges the ghost to speak, not Hamlet. Not only does Horatio challenge the ghost to speak, but he challenges the ghost to speak multiple times. This is important because there is often a debate among scholars as to whether the ghost is “honest” or not. Horatio, being a very honorable character, can be seen to have a bit of intuition in the first scene when he puts forth these interesting challenges. After the ghost causes Horatio to harrow “in fear and wonder,” it is in line 48 that he first asks the ghost “By heaven I charge thee, speak.” Now, yes, it is Marcellus who begs Horatio to do so with the words, “Speak to it, Horatio.” One imagines a cowardly friend pulling on the arm of a buddy who is more brave. Horatio doesn’t stop there. Line 51 reads, “Stay! Speak, speak. I charge thee, speak.” Then the ghost exits and reenters, and Horatio says again in line 127, “Stay, illusion. . . If thou has any sound or use of voice, speak to me.” Then further, “If there be any good thing to be done that may to thee do ease and grace to me, speak to me.” By line 135, Horatio is yelling, “O, speak!” In line 139, Horatio says again, “Speak of it. Stay and speak. Stop it, Marcellus.” It is then that the ghost is seen no more. The interesting thing to note there is that Horatio asks the ghost to speak no less than nine times within only 100 lines. What is also interesting is that Horatio calls the ghost an “illusion,” not something of reality. Further, it’s important to note the condition as to which Horatio wants the ghost to speak. Horatio asks the ghost to speak only “if there be any good thing to be done that may to thee do ease and grace to me.” This is precisely the debate among many scholars. Does the ghost have any desire to do “grace” to good characters like Horatio and Hamlet? Or is the ghost’s main goal to damn characters like Horatio and Hamlet to a fiery hell?