Excessive, but understandable. Remember, the Hood (or the voice on the phone claiming to be the Hood, although the murder of the teacher seems to confirm it) said that he's committing these crimes for Betty. She undoubtedly feels some sense of guilt or responsibility for all this, and she's driven to do something about it. And that made her desperate. As Veronica said, she mistook wanting an answer for having one. (Which is a marvelously concise statement of an important principle. Veronica continues to amaze me.) After all, as fundamentally decent as the core foursome are, they're still teenagers, and they're being forced to deal with matters even adults would find challenging. So they kind of have a tendency to make bad decisions.