You can safely withdraw 4% a year from a nest egg to retire.
20k a week is probably 550k a year take home after tax. If he saved every single penny over a three year deal, he would have a whopping 1.6 million in the bank which at 4% gives him 65k a year.
If he saved half of it instead which is likely more realistic because he’s a footballer hanging around with other footballers, he’d have secured the salary of an experienced postman.
Of course the logical thing to do is maximise his salary, any other talk is nonsense and jealousy