Why do beginners often think they know more than experts?
The less someone knows, the more sure they often are.
People with limited knowledge in a domain tend to overestimate their own competence, while genuine experts often underestimate theirs. The core problem is that the same skills needed to do a task well are also needed to recognize when you're doing it poorly.
A beginner after one tutorial feels ready to teach; the expert keeps spotting what they still don't know.
You need knowledge to know what you don't know.
Loud certainty isn't proof of skill - in yourself or others, check the track record, not the confidence.
Too little knowledge to see your own gaps.
Learn the idea and practice English at the same time.