I have been on messageboards since the days of BBS. I have observed and encountered many individuals who are seemingly hostile over the years.
The internet is an anonymous place and people are not held accountable for their statements. For certain guys, it gives them a feeling of power when they put an idea or person down. Since they wont be held accountable for their speech, ultimately, they post whatever they feel no matter how tasteless or rude it may seem.
The only way to stop them is to simply ignore them and not play into their hand. Many folks attempt to reply back, but that just fuels the fire and satisfies the original poster even more.
It does seem rather interesting where these financial discussion boards can attract an unsavory egotistical crowd. Sometimes I wonder why other types of message boards can remain so civilized where as these financial boards seem like the wild west.