Is there a specific amount you think they gain from not giving a damn about privacy? $5B is a lot of money! I worry that if you think it's "basically nothing", you would've thought that no matter how much it was.
But you're equivocating here. They're allowed to not give a damn about privacy in the broad sense you're using; the FTC fined them only for the small subset they weren't allowed to do.
If you think the government ought to just ban Facebook, sure, whatever, but that's not the FTC's job.