I'm a professional developer for over 10 years now and was doing private dev stuff since 2000. I studied computer science (bachelor and master) and still often think I'm an idiot.
I have some ideas why this could be.
First, Twitter, haha. I follow some pretty highly skilled developers and always have the feeling I'm surrounded by brilliant minds, which makes me feel dumb. On the other hand probably <100 of the people I follow are such pros, so it's a really distorted feeling.
Second, as a dev I do new stuff all the time. Yes, I don't do one React-Native project here and then switch to HFT and then build a filesystem, but still, things are changing rather fast and every project brings its own problems to solve. Yesterday I told someone what a monad is, tomorrow I'm going crazy because the React-Native update doesn't work. A bit like "I got back from my space flight... so how does this microwave works... ah guess its bread today!"
Also, I have the feeling I'm not a fast learner. I learned to swim with 9 and riding a bike with 13, I had to do the 4th grade two times. I studied CS, but it took me much longer than the average student and I had to wait about 3 years until I got a place at an university, because my grades were so bad. Now I work as an mobile developer, this job doesn't even need a CS degree. So every time I learn something new I feel like it's some outdated crap everyone knew years before me.
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