A person's success is always influenced by many things and not only from his school, because at school everyone is learning to gain knowledge and then use it in life. That is, the school is only trying to provide useful lessons so that students become smart, not ensuring that each student will be successful simultaneously at the same job. So it's really not right if you only judge a person's success through his intelligence while at school, because there are still many things he needs to face when he's outside of school.
So that someone who wants to be successful must always have more experience and must be able to get used to being smart in getting along with the surrounding environment. Because being smart at school still doesn't guarantee someone can easily succeed when in a community environment.
success is a process and as you said it is also influenced by many things,
the most important thing is that intelligence needs to be managed properly in order to produce success.