A post gives good examples to distinguish "important to" and "important for"
- "It is important for you to get well" ~ your life will be improved by returning to health
- "It is important to your family that you get well" ~ they put a high value on you being healthy.
Apply those "rules" to the following example (adapted from another related post)
Schoolwork is very important for Bob to become a doctor.
Which means Bob's life will be improved by becoming a doctor. Who could be the speaker? The common possibilities would be Bob's parents, Bob's friends, Bob himself.
What if Bob himself doesn't want to be a doctor? So, the situation becomes
Bob's mother says: "Schoolwork is very important for Bob to become a doctor."
Bob says to his best friend: "To be honest, becoming a doctor is not that important to me."
It is my understanding correct?