It seems to me that this applies especially to philosophy, the one academic field where virtually everything is contentious (even, I'll admit, this very statement). Philosophers can perfectly rationally disagree, and disagree radically, in their views of at least:
* what counts as an important topic,Those of them with any sense will then choose, in their own research, to focus on the most important topics, using the best approaches and arguments, wisely defending the truth. By their own standards -- and quite reasonably so -- their work will be the best stuff out there, with the exception probably of a few acknowledged heroes after whom they mold themselves.
* what is a good method to address a particular topic,
* the truth of almost any philosophical conclusion,
* the quality of almost any philosophical argument.
Almost inevitably then, almost everyone who does philosophical research will feel that their work is undervalued and underappreciated by the rest of the community (who for their part very reasonably have different standards). Aggravating this will be the usual self-serving biases and positive self-illusions of non-depressed people, and various cognitive and situational facts somewhere between self-deceptive and rational. To exemplify the last point: One's own work is more salient and better remembered than that of others, and so more noticeably missing from reference lists. Positive feedback is more likely to be conveyed than negative feedback, especially as one's power and prestige increase. Like-minded philosophers tend to aggregate in departments, in conferences, in journals, in reference lists -- making those with the highest opinion of you and the most similar values the ones you are most likely to interact with.
Odds are, you're about an order of magnitude worse a philosopher than you think you are. Or, put differently: Sure, you're well above average, by your own reasonable standards, but so is everybody.
Update Sept. 10: Let me add that I think the dynamics for students are a bit different, with a substantial proportion suffering from underconfidence. Or actually, I think more commonly among top students (including in my own case when I was a student), there's a weird, irrational blend of underconfidence and inflated arrogance.