I think both fans & supporters attend. Those who no longer do or rarely have are followers.
Those who do attend, in general, seem to have little time for followers. It appears if you don't go your opinion is invalid, unless your opinion agrees with the fan/supporter, in which case your opinion is accepted. A drunken, trouble making knobhead who attends, being a fan/supporter will expect his views accepted by other fan/supporters, or so they believe.