Chris Brown's career has taken a huge hit, I don't see that happening with Bieber. Chris Brown has 10 million twitter followers, and he managed to get in his first week of his last album being out....135k. He got outsold by 2 Chainz. I don't know about you, but I never see that happening with Bieber. Even if he get's in a domestic abuse case, he has way too many fangirls that would go the "I don't care if he punches me I just wanna be with him!!111" route.
Well, thats because those teenage girls will buy anything Bieber related.
My point is, Bieber is somewhat of a bigger star than Chris and always has been, hence his albums have all reached number 1. But the fact that he gets most of those sales from teenage girls makes people dislike him even more and downplay his talent, when it's obvious he's talented as hell.
Okay, so Bieber might not turn out exactly like Chris but by being in the limelight so long, he likely will veer off course.
A Chris Brown situation will never happen to Bieber because Rihanna had a history of violence and Bieber and Gomez are part of the Disney crowd so their images will be squeaky clean.
Edit: At this point, Chris Brown is hated more than Justin Bieber. Most people can't give a legit reason for why they hate Bieber as a person besides stuff like his music or his look but people who hate Chris Brown will always refer to the Rihanna incident. Chris Brown has even been blacklisted in certain places.
The same Disney crowd that Brittney Spears, Miley Cyrus, Demi Lovato, the black dude from That's So Raven that got busted with weed were all part of? Eventually, they all grew up. That Disney tag doesn't stick around forever.
As for Brown being hated more, I doubt it. People have a reason to dislike him but I think some of that hate faded away. His first post Rihanna album had the worst first week numbers of his career, at 102k. But, the very next album reached 270k, just shy of the 295k his second album did. He still sells out shows, still maintains various friendships throughout the music business. Hell, a case could be made for Michael Jackson being more hated than Bieber and again, it would be for legit reasons.
But with Bieber, its like "just because".