When it comes to credit cards, Kevin O'Leary and Dave Ramsey may as well live on different planets. O'Leary, famously known as "Mr. Wonderful" from "Shark Tank," believes the problem isn't plastic — it's people. In a November post on X, he laid out his personal system: "Credit cards aren't evil, bad discipline is." He uses three cards, all with clear roles: one with a high limit he never touches online, another capped at $2,500 for digital transactions, and a third joint card strictly for shared househol ...