Your point is dangerous: learning second language after reaching 18 is too late. This is a torture to most people, unless someone is extremely telanted with languages.

As we learned from linguistic and physiologic experts, it is critical for kids to learn their languages as early as possible due to the nature of human brain development. Starting before 3 is ideal. After 6, one might got some accents. After18, your need a tongue twister operations from language teachers.

Please stop misleading people. Even though you have your point, please don't forget to consider the word of consequences, which obviously you didn't learn well from the east wisdoms.

Suggest you get on the google to see the difference between Chess and Weiqi (Go). You should learn something there.