No, I don’t think human behavior defaults to bad; sorry if my expression communicated that.

I don’t know nor can I predict each person’s default behavior.

I suppose when I say people are people, I mean: they are complex.

Yes, this man’s behavior was bad and unacceptable…but I suppose what I’m getting at:

Following up in agreement with your comment that when we think we understand and can predict their behavior—humans will easily destroy that prediction and do the inconceivable.