You should have grown up in Portugal. 90% (not exaggerating) of the people in my school were Benfica fans. We're 350 km away from Lisbon... I support my local team Beira-Mar, and in a school 30 minutes away from their stadium I was their only fan as far as I know. Sure, some kids "support" them, as a 2nd team.
A home match with 26 or 27k away fans in a 30k stadium is quite the frustrating experience, especially when most of them are from your own city and even go as far as making fun of their own city's club.
Nothing better than when we beat one of those big clubs though, even if it only happens once every couple of years.