I know loads of Greek Australians who spent thousands of dollars going to Europe to watch Greece win the European Championship in 04, and then saved up and went back to Germany to watch Australia play in 06.
Clearly there was no lack of passion. People's allegiances to national teams just have a different dynamic to their allegiances to clubs.
And even then, it's no uncommon to see English football fans from places like Colchester or Swindon who passionately follow a Premier League club, even following them home and away, while occasionally attending their local club's matches in League 1.
It happens.