When massive trauma hits, some people try to find any way to make sense of what seems senseless. Find any semblance of control, of responsibility.
Lilo may be blaming herself (unfairly) for her parents’ death. This was the only connection she could make, the only thing she could have had any control over, so to her it must have been her fault. If only she was a good girl. If only she did the right thing. Then maybe…
It’s very very hard to lose a mindset like that even when it’s the most irrational thing, even when it hurts you, because then you’re left with nothing.