The bad guys in movies and media are almost always bald.
Professor X:Hey, kid, are you saying that I am a bad person? I will change your will.
That's a good one. Patrick Stewart played some of the nicest and most honorable characters. I really liked him as Cpt. Picard.
I'll add actors like Jason Statham and Bruce Willis, who usually play the good guys. There's no rule that says bald = bad.
I think he means that something like this is going to be the exception, and sure as shit not the rule.
Also, this isn't saying that bald people aren't going to be successful in life. It's just pointing out that in society it is fine to make fun of someones looks when it falls under certain categories (OP is talking about, in particular, being bald) but you can't do it (or it's frowned upon) if you're making fun of someone's weight.
The double standard is all it is, really.
Fine, I agree that it's seen like a person is lacking in some way. Short or skinny people could say the same. There's this stereotype of Mr. Perfect. A man must be tall, fit, preferably with dark hair, visible but trimmed facial hair, strong chin. Is the life a bit harder when you're short, fat and bald? Probably yes, but don't make a big deal out of it.
Out of the guys over 30 that I know, 2 are visibly going bald, and the better way to go bald is from the front towards the back, like one of them. The other one is not that lucky, and is starting to look like a medieval monk. Nobody is making fun of it though.