I have a theory on this. It is only a theory, and I'm going to throw some completely made up statistics into the mix.
My belief is that 99% of GTSport players start a race with a clean mindset and want to race cleanly. 1% are out to cause havoc regardless.
The trouble starts when there is some form of contact between two cars. One of the drivers goes "HOW DARE YOU TOUCH MY CAR" and retaliates. I reckon something like 30-40% of racers are like this. This causes a ripple effect causing other people issues, more contact, and more retaliation.
In my early days of GTSport I went through this phase. It was only brief as I very quickly realised two things.
1. Retaliating will both harm your own SR and your own finishing position.
2. YOU MIGHT RETALIATE AGAINST THE WRONG PERSON! (I've been on both sides of this).
Sorry to say I have been that guy. I essentially now race clean at all costs.
Everyone has a fuse of a different length. For some people the lightest of touches is all it takes, for others it has to be consistent dirty driving from another before the retaliation kicks in.
When I see two drivers going at it it makes me happy as it means I'm about to pick up a position or two
I'm also careful to not take advantage of accidental contact, and to give a position back if I've won it unfairly. I see others doing this too but I reckon that's about 10% of racers according to my made up stats