Working backwards from cui bono gets you exactly the kind of reasoning you’re talking about here, because you’re assuming an entire chain of actions from an endpoint that could have been radically different under slightly modified conditions.
Donald Trump got shot at- it must have been the Deep State; they serve to benefit, and everyone know they lie.
Donald Trump got shot at- it must have been Trump; he will now get a boost in popularity, and everyone knows he lies.
Donald Trump gets shot- the media was in on it; they all refused to call it an assassination, and everyone knows they lie. They’re working with the deep state.
Donald Trump gets shot- the media is now reporting it as an assassination attempt; they are working with Trump because he’s click worthy.
All of these scenarios are spun from pre-existing assumptions and the facts are shoved in in ways that rationalize them. Letting the evidence lead the way means taking a step back and asking hard questions not only about what happened, but about what I believe.