And he admitted: "It's the first time I've really messed up. Other chances I've had other people have done very well, this is the first time I've really messed up which is okay. You're entitled to a couple of mess-ups along the way."
I would like to make sure that I get the bolded fragment right. In my opinion, the fragment means "Other people have made a very good use of other chances that/which I've had. In other words, "both other people and I have had other chances, but they have used them well whereas I have ruined them.
Golf: Monty's happy to have more 'disasters'. - Free Online Library