I am going to generalise here, but i think in the majority of cases, it's justified, and borne out by the interviews we see on TBV, and the behaviour we read about -
Young lads in school broadly divide into to two sections - the academic ones who sit in and study and go on to careers, and the sporty ones, who don;t like study, and play outside most of the time, in some cases discovering sports talents that see them as multi-millionaires in their early twenties.
So - a lot of young sports men - but by no means all - are not very bright, but they have to deal with the fame and fortune that comes with the rewards of their talent.
In cases like this, we have a young man in the company of other young men who like the maturity and intelligence to behave like the athletes and national representatives that they are, and revert to type, which is behaving like silly boys because rarely, if ever in their lives, has anyone ever told them not to.
It is to be expected - and t'was ever thus, football and rugby players are this way, and always will be.