They follow the Pareto principle. 20% of people make 80% of noise and 20% of noise creates 80% of responses.
So pretty much regardless of what the topic of the day is, a minority of people will be the loudest and majority of their arguments end up not influencing anything.
Death threats are a perfect example: only a small number of dissatisfied fans actually make them, with most of them never even intending to go through with them... but since threats of extreme violence are being taken seriously by those threatened, they have disproportionate effects on mental well-being and actions of the threatened.