It’s an African/Asian “fan” phenomenon.
They often don’t have any links to show devotion to a club… They won’t be able to see them live as to get into the country probably involves a visa application that will be declined… They have no reason to support Rotherham or Plymouth or Scunthorpe et al.
It’s essentially parasitising off of the success so they have something to gloat about.
And considering their love for the player is what got them interested in the club in the first place, as soon as the player buggers off, so does their love for the club.
See also the quick turnaround in Tanzanian fans we had just because of a single player coming and going…