It's all the Olympic hooligans that get me.
Sure hooliganism is a big problem in football. But it isn't just a problem in national team matches, there is just as much (maybe more) in club games so you cannot link it to nationalism associated with the world cup.
But regarding the Olympics - it is unlikely to generate hooliganism as it mostly involves spectators going along out of curiosity and ability to 'experience' the event, rather than hard core fans of the sport they are watching. In 2012 we got tickets for the women's basketball (all we were allocated from our application) and had a lovely day out with the family. Thoroughly enjoyed it, although neither us, nor most people around us had the slightest clue as to what was going on. In fact they had a short 'primer' before the game to explain how is worked, the scoring etc. Can you imagine needing the same before a football match?