It certainly happens, but how common is it really? I think we tend to notice these cases much more than the boring everyday cases where people do things for straightforward reasons that they’re fully aware of.
Vocalized rationalizations (e.g. “I didn’t want that job anyway” from the Wikipedia article) often don’t reflect actually delusional beliefs about motivation. A person who says such a thing typically is aware that they really did want the job when they applied for it.
People will naturally try to find the best rational justification for their actions post hoc, but it doesn’t follow from this that they hold incorrect beliefs about their original motivations.
Vocalized rationalizations (e.g. “I didn’t want that job anyway” from the Wikipedia article) often don’t reflect actually delusional beliefs about motivation. A person who says such a thing typically is aware that they really did want the job when they applied for it.
People will naturally try to find the best rational justification for their actions post hoc, but it doesn’t follow from this that they hold incorrect beliefs about their original motivations.