Does Othello have impostor syndrome, or any other problem because his background is different? Is there any implication in Shakespeare's text that Othello had impostor syndrome, or any feeling of inadequacy (in love, or another aspect of interpersonal relationships) because his background is different? Something that was made evident/suggested by the text of the play, and could be linked to Othello's background. Logically, since he was much more successful than other men with a similar background, he could have had it. And, if he had it, it could have made him more vulnerable to Iago's lies. Is there any evidence in the text of the play to support this hypothesis?

Most likely, it is the case. His wealth, social status and even marriage were due to his military successes.

In every other matter, he was an outsider, and he was constantly reminded of that. Brabantio told that

> To fall in love with what she feared to look on?
> It is a judgment maimed and most imperfect
> That will confess perfection so could err.

Even his wife, when summoned by the Duke, firstly referred to him as "Moor" and only then as "Othello".

> And so much duty as my mother showed
> To you, preferring you before her father,
> So much I challenge that I may profess
> Due to the Moor my lord.

Most probably, when constantly reminded that he is different, unworthy of love etc. anyone will start feeling inadequate no matter how strong-willed they are.

_(Only adding my own answer as there are no alternative answers. This is the initial version, I will add more details later.)_