I agree that there is a misconception that all Asian languages are impossible to learn. It is possible to learn any L2 provided the learner is reasonably adept at language learning, is highly motivated, has the right learning environment, and is able to stay with it for a long time. That being said, there is considerably less positive transfer from English (L1) to Korean (L2) in terms of phonology, grammar, and vocabulary than, for instance from English to Spanish, French, or German. Ergo, it will take longer to achieve a comparable level of proficiency in Korean vs these languages. This has been shown repeatedly. Detecting regularities (your term is “logical”) certainly helps if you can translate intellectual awareness into actual in-time performance.