I oft reflect on this matter as a teacher. Children very frequently support the big teams, often because they aren't exposed to regular live football at local clubs by their parents.
Instead they get their 'football fix' from football video games, Sky Sports, Match of the Day and so on.
They like to see goals and wins, so support the 'best' clubs. As a result, there is very little loyalty or meaning behind their support.
That's why us Saints fans are dye-in-the-wool steadfasts who feel a real affinity for our club and fellow fans.