Pretty much, they have delusions about their competence and thinking skills, but when it comes to reality they are insecure and lazy most of the time.
Throw in some generic sheltered background and youthful sense of entitlement as well.
That's the first stage of finding a career, to estimate properly one's worth and favourites (getting rid of illusions) and to start working, rather than just evading problems and dreaming about being someone.
This is a problem for a very large fraction of recent college grads, not just INTPs. In fact, I think (more so than other types) INTPs desperately want to find that "one thing" that they can dedicate themselves to, but are held back b/c everything looks so unpromising...and for the most part it is! Most jobs simply do not suit the INTP personality, either because they don't involve enough analysis and creativity, or because there's too much in the way of interacting with people, or it's too repetitive...
Insecurity, sense of entitlement, and sheltered upbringing are traits of many young people nowadays. Especially those coming out of top-tier undergraduate and graduate programs. Alumni reunions at my alma mater were the perfect example of this. "So what do you do?" **anxiously hoping that the other person won't say "I'm a vice president at Goldman Sachs."** It's one big competition when you're young. No one ever asks "So do you feel like you have enough opportunities in your current job to realize your full potential as a human being?"
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It's money and prestige, and everything that goes along with that. As people mature, they stop giving as much of a shit as long as they have their own needs met. Scratch the sense of entitlement that comes from a sheltered upbringing if they grew up in poverty...but there aren't many of those at top schools.
Although I don't really like the thought, I've been beginning to think that maybe INTP is just a form of adolescent childishness that some people grow out of earlier than others (if ever).
Because think about it...most of the INTPs that we notice that are 'successful' had to power their way out of the standard INTP uselessness, using 'J'-like drive or productivity systems that INTPs claim to hate. But maybe everyone hates productivity systems. Maybe it's just hard to do those things for everyone (or a majority). And we rationalize it as "oh I'm an INTP I'm just not good at that."
If you don't like the thought, chances are it ain't true. Some people have a much easier time
getting shit done and procrastination was never a problem for them. Those are J-types. They are intrinsically motivated to bring order to their external lives. I would love to be able to be as productive as ISTJs, but then would I still be as good at coming up with new ideas/theories? Every type has its strengths and weaknesses.
What you describe is very real. INTP is basically analogous to unrealised potential.
The question then becomes whether INTPs actually exist in a personality sense, or the effect is entirely explained developmentally. I'd be surprised if it were so simple.
They exist. And no, it's not developmental.