Usage first arose on internet gaming sites. The exact origins are unknown, but the first part may be a conflation of the words 'sketch' and 'spy', thus referring to the unsavory information-gathering habits of someone who is scifam. The second half of the word, 'fam' may be a shortened form of 'family' thus indicating that unfortunately, there is a large number of people like this, as scifam prefer quantity over quality.
"Dude, that sucks. But I always thought he might be scifam."
"This guys has, like, a couple hundred players following him, but they're all complete n00bs"
"Yeah, quantity over quality - typical scifam!"