Let me tell you that for any attacker or bad person, their best friend is the element of surprise. No matter how well-armed you are if they can manage can get you by surprise they have an extreme advantage and their chances of succeeding are very good.
Darkness adds to their ability to surprise you even more. Just to demonstrate the power of light one study found that lighting reduces crime by 39%. Therefore having a personal portable light source with you is likely to reduce your chances of being a victim in itself.
As a world traveler, I always have a flashlight on my backpack and in my apartment of whatever country I am staying in at the time. I go by the philosophy “better safe than sorry”.
A tactical flashlight’s usefulness goes far beyond simple illumination, however. A good one can temporarily blind an intruder giving you enough time to escape or neutralize him. The strobe or blinking setting is nauseating is very difficult to look at which again will give you enough time to fight or flee. Nowadays you can get one, like I have, with serrated edges which is extremely useful in case you end up in a hand-to-hand combat situation.
What’s best is a flashlight is a very inconspicuous weapon to have with you. You can even check one with you on an airplane. Then there’s the fact that they don’t cost that much so you’ve got nothing to lose by having one and potentially many years of additional life to gain.