Well, for one thing, Jennifer Aniston doesn't really make good choices in her personal life (HOW many guys has she gone through?), and secondly...
Her F.R.I.E.N.D.S. co-stars look at her and say "at least she has a career." Lemme put it that way. Cougar Town is constantly threatened by cancellation... Mr. Sunshine didn't last long (I blame the fact they explained Allyson Janny's character's craziness when they SHOULD have held off on that). And... that's basically it. She may be making stupid movies, but stupid movies is still better than stupid unsold pilots for a stupid TV series.
Still just because he managed to do a successful movie doesn't mean he's gotten his act together. I know that's the assumption right now but I know how these "Behind the Music's" play. We found out later on that things weren't so rosy as they appeared to be.
And I'm sorry but Downey had multiple chances, not just a second one. He got away with far too much and didn't get the same kind of negative reaction from the public that Lindsay did. Same with Charlie Sheen. If it's a guy screwing up we talk about how rebellious they still are. If it's a woman, she's just sad and pathetic.
All celebs have skeletons in the closet. Some get revealed very publicly by themselves, some you don't find out until its too late. Sometimes, they do one really REALLY big thing and that's it. Sometimes it's little things.
Charlie, however? Well, that's Chuck Lorre's fault. He's the one that hired him when he had a history a lot worse than Robert's. Plus, that show was on one season too long even before Charlie fell off the wagon and lost it. Now we got Ashton Kutcher making it even more of an unwatchable joke and it's STILL getting good ratings? The show's been boring as heck since he popped on. I wish they got John Stamos.
Still, I just don't hate anyone enough to be happy they failed. As much as the thought of a 40 year old overweight Miley Cyrus mumbling through old songs at a state fair would bring me a chuckle, I'd actually hate to see that and I don't like her all that much. I quite hate hearing child actor "where are they now" stories that don't have a happy ending. I really don't want Lindsay to screw it all up again, but it's probably going to happen.