what about its predicate?

I don’t understand the 1.

  1. Pop stars who start off as rebels or idealists with strong moral principles.
  2. Then, as soon as they become rich and famous, their values change completely.
  3. What hypocrites!

Do we need a predicate in 1? Which word can match best?

Thanks

You need to remove ‘who’ from (1).

The (1) is one more wrong sentence from my, already mentioned, “exemplary” book about word skills.

  1. Could the below sentence, (4), be accepted as correct?

  2. Pop stars who start off as rebels or idealists with strong moral principles, later on, as soon as they become rich and famous, change their values completely.

In addition, please correct the punctuation in sentence (5) if the punctuation’s wrong or you prefer some other punctuation.

Thanks

4 is not the best constructed sentence I’ve come across, but the ‘who’ works there.
A better construction, in my opinion, would be:
Pop stars who start off as rebels or idealists with strong moral principles, change their values completely as soon as they become rich and famous.

  1. Could sentence (4) below be accepted as correct?