I am not certain that to say Phil was made mad by drunks and drink is accurate; seems to me he was fairly mad from the get-go, as Doc Cheese indicated. Remember, Ronnie Spector fled her young husband when he revealed to her the glass coffin he had installed in their basement, and into which he vowed to install her should she ever leave him. No doubt this was some early bout of amphetamine-fulled psychosis, but it went unchecked, and Phil had the fame, the fortune, and solitude provided by both that allowed his madness to blossom into an ongoing psychosis that as the 70's wore on, because a kind of routine that the business actually encouraged, if only by condoning such bad behavior.
The Ramones told the story many times of Phil brandishing a gun at them to keep them in a session, but it was mostly told in the spirt of braggadocio, the way guys would like to be perceived as being unflappable in such situations. I think in some versions of the story, either Dee Dee or Johnny tell Phil to stuff it. In any case, this was never told as a cautionary tale, but as a lark, a bad bod adventure. Phil no doubt read such "rock lit" and played up the act even more. By the time of Lennon's "Rock and Roll" sessions, Phil was almost always wearing a shoulder holster, and would point to the section with his gun when cuing instrumentation during cacophonous sessions.
And the woman Phil eventually shot was not the only female houseguest to be held at gunpoint in that way. She was merely the final, inevitable one.