I can’t recall now where I read a story saying basically “don’t get a dashcam, because you will then be trying to do impressive stuff all the time”.
Personally, I feel naked now without a dashcam running. I’ve had a series of them in my car for the last few years. I haven’t changed my driving at all because of it - in fact, I all but forget it’s there.
I was rear-ended a year or so ago; my dashcam footage let me show the responding officer that I was correct in my statement that I was at a full stop when the other driver hit me.
I had my wife’s car (without dashcam) when a pretty good accident occurred directly in front of me (close enough that I examined the front of her car to see if it caught any debris). I wished then I had had my car, to be able to provide the not-at-fault driver with some beautiful proof he wasn’t at fault.
It’s similar to my radar detector: I’ve had one hardwired in my cars for probably most of 25 years now. Having it hasn’t changed how fast I drive, it’s just made me feel a bit better about it. When it beeps, I may reduce my speed by a few MPH, but I didn’t install it then cruise any faster.
Anyway, I strongly advocate having a dashcam, and don’t believe having one has had the slightest negative effect on my driving.