This is silly. You people are restricting the term "photographer" to just people who make a living off it. That's ridiculous.
I don't think people have an issue with someone calling themselves a photographer as much as they're trying to determine your qualifications. Because nearly anyone could snap a photo and legitimately call themselves a "photographer".
I'm a computer programmer (yes, it pays the bills and has for many, many years). If a stranger offered me advice on a problem I was having, I would want to know their qualifications. It doesn't mean a "professional" would have the answer to my problem. It doesn't mean the "amateur" would NOT have the answer. It would just be the first step of many that I would use to determine the validity of their opinion. Because I'm NOT going to follow the advice of any old yahoo who stops by with an opinion. I don't even do that with the people I work with.
You don't have to be "paid" to know what you're talking about. So you're a "photographer". Yippee for you. You STILL need to prove your knowledgeable on the subject regardless of if you're a "professional" or "amateur". "Do you make a living taking pictures?" is a quick and easy test to get a general idea of who you're talking to. A place to begin a conversation with a complete stranger. The answer to that question doesn't always paint the whole picture (there are pros who shouldn't be and amateurs perfectly qualified to be), but it is a starting point. I'd listen to a knowledgeable amateur over an idiot professional. But I'd expect that situation to occur far more infrequently than a knowledgeable pro vs. a idiot amateur.
So, someone questions your qualifications. Big deal. Prove your qualifications or admit that you don't know as much as you think you do and learn something. I've mentioned I'm a programmer. If I was commenting here on that topic, I'd have no problem proving I know what I'm talking about and not just blowing hot air. I wouldn't be offended if someone questioned me. They don't know me. They should question me. There are other topics I know plenty about. Topics I'd have no problem discussing with people. I don't get paid to do those things and would readily admit that if questioned. But I would also prove my knowledge of the subject in other ways and not just get offended that someone wanted to know if I do it professionally.
On this particular topic, I know enough to follow the conversation. I think I know enough to know which side knows what they're talking about and which side is confused about reality. I'm not a pro. I have no opinions I can back up with facts. So I'm taking a back seat and learning.