In both cases, who is being used as a restrictive relative clause—meaning that the speaker/writer has decided that it is essential information for the sentence. If there were commas, it would be non restrictive (meaning just adding extra information).
That being said, the second who is not entirely necessary (because the “individuals” being described are the same as the “people” being described by the first who). Therefore, I would rewrite the sentence like this:
People who prosper tend to strive to do their jobs well, spend less than they learn, and save for the future.
I hope that helps!