How to deal with online DBags/Aholes?

okay, so yes, this is the internet and no matter what you say, there will Always be someone who says “well actually…” or “well technically…” there is Always someone who wants to prove you wrong for some reason. These people never seem to go away and are always dicks. Clearly if I’m on a bodybuilding forum asking something, then I’ve tried googling/binging and/or searching the InterF*ckingNet and/or forums but could not find an answer.
Why do people feel the need to sh*t on eachother all the time?
why can’t people be more positive and actually either HELP or keep their mouth shut if they have nothing positive/good to say?

also if I start the paragraph in the discussion by saying “if you blabla then don’t answer” I’m the one who sounds like an a**.

what do you guys think, recently there was an answer that made me think for a whole freaking week, whether or not I should risk getting banned from that forum and reply to the guy, or just let it go. I understand that some of these people might just be young punks or simply idiots, but Sometimes these things get to me.
If you have a thick skin, good for you, but there are some things that I just can not ignore… =)
thanks
with love…