When I read a thread where reactive comments can cause unrest, I look less at content and more at behavior. While most commenters are not antagonistic, one commenter continues to be just that. In the virtual world this person is often labeled a Troll, those who purposefully intend to rouse the ire of others. While it's sometimes difficult to ignore a Troll, it's the best course to get them to move on.
However, in this case, there's another explanation tied to behavior. So let's go to the Mayo (Clinic):
Narcissistic personality disorder is a mental disorder in which people have an inflated sense of their own importance, a deep need for admiration and a lack of empathy for others. But behind this mask of ultra-confidence lies a fragile self-esteem that's vulnerable to the slightest criticism.
A narcissistic personality disorder causes problems in many areas of life, such as relationships, work, school or financial affairs. You may be generally unhappy and disappointed when you're not given the special favors or admiration you believe you deserve. Others may not enjoy being around you, and you may find your relationships unfulfilling.
Criteria for narcissistic personality disorder include these features:
•Having an exaggerated sense of self-importance
•Expecting to be recognized as superior even without achievements that warrant it
•Exaggerating your achievements and talents
•Being preoccupied with fantasies about success, power, brilliance, beauty or the perfect mate
•Believing that you are superior and can only be understood by or associate with equally special people
•Requiring constant admiration
•Having a sense of entitlement
•Expecting special favors and unquestioning compliance with your expectations
•Taking advantage of others to get what you want
•Having an inability or unwillingness to recognize the needs and feelings of others
•Being envious of others and believing others envy you
•Behaving in an arrogant or haughty manner
It's not known what causes narcissistic personality disorder. As with other mental disorders, the cause is likely complex. Narcissistic personality disorder may be linked to:
•Mismatches in parent-child relationships with either excessive pampering or excessive criticism
•Genetics or psychobiology — the connection between the brain and behavior and thinking
So while there's treatment for this disorder, many don't seek it. Instead, they show up in places where the majority find them uncomfortable to associate with. It must be a joyless existence and in fact we evidence that by seeing it in words and photos. Take from this what you want and reach a happy place with how you decide to deal with it.