There's a lot of hate towards the Beta Testers after the first month, in which 2000 people die. The common SAO player blames Beta Testers for farming the good EXP and loot drops, and not helping other players, and for being assholes who couldn't see that the game was flawed. In fact, one player is ready to lead a jihad against all Beta Testers for their supposed crimes.
Relatively speaking, however, casualties among beta testers are higher than normal players.
At the end of a large battle, Kirito, after getting Last Attack on the boss, tells the jihad player not to lump him with other beta testers, who were just lucky to get into the game, and that he's a Beater (Beta + Cheater), someone who's totally on a different level from your ordinary Beta tester, most of whom were novices at MMOs. (Irony: he was an MMO novice the same.
)
He deliberately sets himself out to be hated, so that the few friends he has who are Beta Testers won't be hunted down by vengeful jihadis.
After this, Betas are split into Ordinary Beta Testers, normal people who just had some advance knowledge, and Beaters, Beta Tester Cheaters who use their knowledge to exploit the system and screw over everyone else. Betas aren't too bad off, but Beaters are shunned.
Also, if he'd been honest from the start, Black Cats of the Full Moon wouldn't have been in that position. His concealment of that fact led to their demise from biting off more than they could chew.