Step 1 is realizing you're discussing with someone who's hostile by default to you. That's what's missed by all the types whose style of debating relies upon pointing out logical fallacies in arguments -- the fact that debate spaces have not been sterilized against problems of a social nature, and no amount of sound object-level reasoning will fix that. There's always going to be a crowd hanging around a comment section that's there to bring you down and for no other purpose.
From here, you can go in two different directions. Either play on the "battle of wits" mode, return the hostility, do your damnedest to humiliate the other in a way that makes you look good rather than petty, or try to bring the hostile arguer... well, not to your side, but to a neutral basis of discussion. Getting people to just give you a chance, let alone playing that chance well, is amazingly difficult. At least on LW there's a consensus that we should be aiming for the second mode of discussion, but if that's not a constant occurrence here, imagine how bad other places have it.
The attitude you listed is just one of the many tricks people employ to make your life hard, to narrow down the winning condition in an attempt to disqualify as many people as possible from passing the test. The only answer that would kick the asker down a step or two would be "as a matter of fact yes, I am an economist."
as a matter of fact yes, I am an economist
My favourite instance of this merely because of its antecedent improbability.
[EDITED to fxi tpyo]
Especially in the comments of political articles or about economic issues I find myself arguing with people who question my authority about a topic rather than refute my arguments.
----
Examples may be:
1:
Me: I think money printing by the Fed will cause inflation if they continue like this.
Random commenter: Are you an economist?
Me: I am not, but it's not relevant.
Random commenter: Ok, so you are clueless.
2:
Me: The current strategy to fight terror is not working because ISIS is growing.
Random commenter: What would you do to stop terrorism?
Me: I have an idea of what I would do, but it's not relevant because I'm not an expert, but do you think the current strategy is working?
Random commenter: So you don't know what you are talking about.
----
It is not about my opinions above, or even if I am right or not, I would gladly change my opinion after a debate, but I think that I am being disqualified unfairly.
If I am right, how should I answer or continue these conversations?