Ivan Boastky
Da infamous "insider trading" crook who got busted 'cuz he couldn't resist regaling everyone with braggardly tales about da windfall profits of his clever sneakiness.
If Ivan Boastky had just kept his mouth shut, he might have gotten away with his chicanery, just as Odysseys could likely have escaped da cyclops's wrath if he'd just quietly sailed away, rather than loudly shouting his triumph at having outsmarted said murderous giant.