What is the purpose of saying, "being a Korean with a college
degree is wonderful"?

Not too sure about this one but maybe it shows the value of education in Korea.
I do notice how competitive it is to earn a college degree in Korea, students stay up all night studying every single second to score even one point better in their entrance exams, something like SAT in the US, so they can get into the college they want to.
The better college you go to, the better job you get. Now that’s common sense but the value of that is different from the US. There’s the “American Dream” in the US where anyone can become rich if they put their mind to it and luck rolls on, in most Asian countries academic history/resume is what determines their life.
Sorry that was a bit all over the place but hopefully you got something from it

Betray, destroy, and obey do not need to be changed to add the suffix -ed, because the "y" at the end of each word is preceded by a vowel  (so  they would be spelled  "betrayed," "destroyed," and "obeyed").

but hurry is different; it has to  be spelled "hurried" because the "y" at the end of "hurry" is preceded by a consonant.