@Fuzzy Thunderbear . . .
Well - Isn't this an interesting conversation to come across today. . .
As for whether or not I can help Ya' understand why it is happening, that's very debatable, especially since I am still trying to figure a lot of it out "Myself" at times and do not have an absolute answer . . .However, I will try to give "You" some reasoning behind this kind of attitude and how it is manifested into this type of behaviour that without a doubt has become more acceptable to a number of people than it did in the past . . .
NOW - As has already been mentioned, some of the reasons that people came up with are quite true and are actually very much factors . . . Such as:
AND - While all these opinions are factors in why people behave as they do today, it really comes down to the social constructs and constraints in which the majority of society is willing to accept as appropriate behaviour, particularly when it comes to what is continually allowed by others (The majority) who do not speak up about what is not going to be acceptable - nor allowed . . . More specifically, it really comes down to Common Basic Civility and the loss of same when people as a whole started to become even more self-centered as being more important than and not caring about anyone else - but themselves too.
ABSOLUTELY - NOT ! ! !
It actually started a long time ago . . .
Now - I could go on and explain a number of other factors that lead up to this, including all the changes in how people communicate with each other personally today compared the past . . . Matter of fact, one of the post "You" had in another thread (I think is was on the porch) a while ago spoke very well about the difficulty of being able to read the intent of a post and how people could misinterpret them very easily depending on their own perspective/s . . . However staying specifically with why "You" asked this question . . . "note a great deal of hostility, anger, people being huge jerks for apparently no reason at all." . . .
IMO, both personally & professionally - the loss of Common Basic Civility came about with the continued rise of Social Media as a norm to express oneself and when society started to accept that it was alright that people could do as they wished and actually encouraged them to do so on the Internet . . . AND - Since some people believe that the Internet allows them the anonymity to say what they wish and can get away with disruptive/abusive comments on forums all because they get some form of sick satisfaction of power/control . . . The worse part is that it does and there are many others who will "egg" them on too . . . So - Screaming out insults as a way of getting attention or getting your point/opinion across - has essentially become the "Norm" . . .
Just as an example: Look at what happen when President Barack Obama was giving his National Address to Congress & the Nation in 2009 and that Senator screamed out "You Lie" . . .Nothing was done, no one "hushed"/stopped him, nor even reprimanded him at the time from what we know . . . AND - Whether or not the Senator was correct in his assertion doesn't matter
(And BTW: President Obama didn't lie), it should never had been done at that time - nor should it have been accepted . . . The Senator should have expressed his personal opinion to the press after the Presidential address . . . Just Sayin' . . .
Hope that at least touches a little bit on the why it will sometimes happen . . .
BTW: A DISCLAIMER - While I am a Counselor in Human Behaviour Modification, what has been written in this post is by no way the be all end all - nor as the only answer to this type of situation . . . The wordage used are, as always "My" Personal & Professional Opinion from "My" Experiences and Knowledge Base . . . If "You" disagree with what I have said in this post or have "Your" own opinion - GREAT ! ! ! This one is "MINE" ! ! !
...Lasagna sounds good...we're still trying to decide what we're going to eat here...looks like take out, but not sure what yet.
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Millennials! 
