Some weeks ago I was at a philosopher dinner with someone who's a local philosophy professor, and as the evening were wrapping up I mentioned gentleman-scholars and we had a brief discussion of what it means to do philosophy; he remarked that to him, there should be two terms, 「amateur philosopher」 and 「philosopher」, the latter either being employed as a philosopher or published and the former not necessarily being so. I mentioned that I use a different world-of-terms for that; 「philosopher」 being the general term and 「professional philosopher」 being the person who makes a living out of it (being published not really mattering to me).
Neutrally, the question could be asked, if we agree that professional philosophers are making a living out of it and nonprofessional philosophers are not, to whom does the unqualified term refer to? We might look at two terms: artists and doctors. Being an artist is primarily based on a self-declaration; if one identifies as an artist, one can do so, and most people's categories for who-is-an-artist depends primarily on proferred identity as well as possibly some other qualifiers (like "makes art" as a reasonable life-focus/hobby). Being a doctor, by contrast, is mostly a controlled term; one might self-identify as a doctor, but other people won't categorise one as such without having certain degrees and experience. Some allowances for differences betwen societies are generally made; we might look to a theoretical authority to identify doctors in our country, but we'd probably recognise different authorities for other countries to determine doctorhood within their borders. A third example, not particularly helpful, is presumed recognition in martial arts; there I suspect people might be all over the map in what they recognise, from not recognising anything/not having frameworks at all to recognising multiple authorities based on size of a martial arts organisation to other frameworks.
I choose between the models for the self-declaration (plus possibly works) being sufficient for the unqualified term model for a few reasons:
Philosophy is primarily based on two things: knowing relevant things (often the ideas of other philosophers) and being able to think flexibly about them. As a solitary trade based primarily around ideas and talking, a philosopher's works might build with equal footing on that from contemporary and local colleagues as those from a distant land and distant century. Philosophy is also more naturally divergent, meaning the work of ancient (and often non-professional, non-academic) philosophers, if introduced today, would uusually merit equal attention now as in their original time and place. I hold that these things suggest a universal equality of philosophers, where they are judged by their ideas and their expressions, not by whether that's how they make a living; the professional philosopher is just a philosopher who's found a way to make that their profession. That's great and good for them, but it doesn't merit any more respect or attention; even the idea that the respect of other academic philosophers is important is unimportant; like only a few other professions, the most solid way to judge a philosopher is from long after their death.