The general rule is that every person is obligated to have Bitachon in proportion to his Emunah. The amount is different for each person.
Emunah is belief in Hashem and His Hashgacha. Bitachon is relying on Hashem to protect and take care of you. So while an average person would not be allowed, for example, to stick his foot in a snake pit, Rabi Chanina ben Dosa could, because, although we all know that "it is not the serpent that kills but the sin", because to Rabi Chanina that concept was as clear and as obvious as day, he is allowed to put his foot in that pit. We cannot.
Also, Yosef haTzadik was faulted for relying on a royal officer to help him get out of prison. He should have relied on Hashem only. Even though we would not be held accountable for such normal Hishtadlus, someone on Yosef's level should have had more Bitachon and relied less on Hishtadlus.
So the rule is, it depends on who you are. If you are a great Tzadik and Baal Emunah then you must have more Bitachon and less Hishtadlus. And vice versa.
Therefore, the answer to your question in real life is that unless you are a great Baal Emunah, you may not rely on anything less than normal, natural Hishtadlus. Meaning, you must do everything as if there would be no such thing as Hashgacha, as if everything depended on nature, and then, you must know in your mind and heart that it is all from Hashem. See here. Although Hashgacha is what runs your life, you cannot rely on it to replace any Hishtadlus.
Therefore, if you take Hashgacha out of the equation - let's make believe it does not exist - would you walk at night in that bad neighborhood? If the answer is no, then you should not do it and you cannot say it was "Bashert." However, if you did something that would be safe if you only consider the Derech HaTevah, or you tried to do what was safe - for example, you had all reason to believe the neighborhood was safe but it really wasn't - if you did your required Hishtadlus, then you can say whatever happened was Bashert and a message from Hashem.