I dont say "fake fan". In my vocabulary, thats a fan that switches teams to support (or claims he supports) depending on who's winning.
But there is a diffrence between real fans that support the team, and "followers". The latter "like" a team, and will follow it if its doing well.
Like, i'll allways watch the juve game. When i watch e-sports, i'll allways watch Naniwa (sc2) (well, watched), and Gambit (LoL). There are plenty other teams i see matches from, but usually only when they matter, are against big teams, and if its a replay from a game they won.
The diffrence between fan and follower in a nutshell