How to debate when authority is questioned, but really not needed?

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.

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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.

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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?