The majority of getbiggers who make fun of pros do it out of jealousy.
Most people here have a feeling that if they can make fun of others it makes up for their own lackings. These people wouldn't be able to make fun of pros in "real life" so they seek the satisfaction of quelling their insecurities by making fun of them from anonymous accounts while hiding behind their computer.
Not only in making fun of pros, but it's this same insecure/jealous persona that makes most getbiggers try to deny wealthy guys like Xfactor when he posts pics of his cars or house, or put down other members' girlfriend/wife when they are hotter than theirs, or put down big guys for being "fat" or guys in good shape for only being "okay if you are a natty," etc. It's all inter-connected and explains the same typical jealous and insecure getbig persona.
90% of getbiggers would crumble if they were assessed by their own standards when it comes to physique, wealth, girls, etc.