Narcissism is a continous trait that to some degree is present in everybody. How could it not be? It pertains to self-worth and social comparisons and no man is an island.
Narcissism is also probably more complex than the implicit assumption of it being unidimensional. There are several ways of conceptualizing it. (benign, malign, envy etc....)
The individual you mentioned has pathological narcissism because it has a psychotic quality that probably hurt his ability to function socially. Suckmymuscle's portrayal of himself did not match how others saw him, he lost touch with reality.
NN
Groinks is extreme because he takes risks, no father should be taking.
Does steriods, is around drug dealers, starts flame wars with a disturbia, puts himself on display, on a board full of fucked up people.