Yeah, feeling safe while riding and actually riding safely are two things most cyclist do not understand.
Most cyclist will feel safe riding with a helmet, lights, reflective clothing, in a park, or on low traffic road but
that will let their guard down and the probability of making mistakes rises.
In contrast riding safely entails 100% awareness and focus in ones surroundings, the ability to anticipate obstacles and obstructions. The ability to proactively take charge of every situation that comes along. This is regardless of helmets, fluorescent clothing, lights, horns, traffic laws.
Remember, cyclists that ride safely will not put their life into the hands of motorists.
I think you are correct that feeling safe can undermine riding safely because you assume too much.
But a question: I was out riding the other morning around 7:45, as folks trying to be to work by 8:00 started zipping around. Country road, not much traffic, no shoulder, white line right on edge of road, narrow road, double line. The sun was coming up, facing me, making it very difficult to see what traffic was coming the other way. I see a car ahead coming in my direction in the other lane.
A big truck with a trailer comes up behind me. I turn and look at them, they keep coming. I point at the car coming the other way, then put my arm out, palm open in the "back off" sign. As I do this the truck comes around me and if I hadn't turned and seen it and pulled my arm in, I think he would have hit me. His trailer predictably swayed too as he passed.
What else could I have done in this situation?
The only thing I can think of is to move over far enough to the left that he couldn't pass me, but I also don't know if getting in the way of an aggressive, reckless dude in a rush in a big truck is a good idea either.
(I don't think someone in a big truck in a morning rush would have taken kindly to me taking the lane).