If powerful people were afraid they would be a lot less unhinged.
We're talking about sociopaths, not people like you and me.
How much of a percentage that is on that level, we can guess.
In particular, terroristic violence almost always incites spiteful reaction against the perpetrators and anyone associated with them.
People like Carnegie built 1500 public libraries because he knew the game. He knew that his position as part of the ultra-wealthy made him a target, and he had to toe a line. He need to maximize exploitation but not too much, so as to not cause a stir. He did a pretty good job. Some people didn't do such a good job - we don't hear about them because they and their families were murdered.
Rich people today are much safer, mostly due to people being better people and technology.