The example of a man who said "I have a masters degree in computer science, so I'm basically a genius." is a prime example of the fallacy of argumentum ad ignorantiam, where one uses their perceived authority or expertise to justify their own ignorance.
Another example is a politician who claimed "I know more about economics than any expert, I've watched all the episodes of The Price is Right.", who then uses their "expertise" to justify policies that have disastrous consequences.
And let's not forget the example of a self-proclaimed "influencer" who thinks they're a expert in everything, despite having no qualifications or credentials, simply because they're "famous on social media".