I don't understand why you are separating the idea of The Joker running a business and and The Joker engaging in criminal activity to climb to the top. In the case of Leto's Joker or comics featuring Joker doing as much, they are essentially one and the same. If The Joker has investments in anything, whether it be weapons rackets, chemicals, or drug trafficking, that is business of the criminal, illegitimate kind. If he's out to gain control of the criminal underworld and will do whatever necessary to climb to the top or finance his operations, including theft and murder, that is engaging in criminal business. If he's looking to gain territory for himself and his gang, and he takes control of clubs or business establishments to do so and uses those locations as headquarters for his operations/plans, that is engaging in criminal business to rise to the top. It just seems like you've been really thrown by the fact that they likened him to a successful businessman and are stuck on the term itself, maybe because you're picturing him as a real-world businessman. All that technically means is he has power and control of his own criminal organization, and that he's smart, good at what he does, and is successful in getting what he wants. It does NOT make him any less of a criminal or wildcard. It doesn't mean he's sitting back and running any kind of legitimate, crime-free business that he built by staying on the straight and narrow all of his life and out of trouble, and it definitely doesn't automatically change the fabric of the character. It just cements the idea that he's a ruthless and effective criminal mastermind at this point in time, with a successful organization in his grasp. It also doesn't mean he's always been in this exact place in life, or that he'll always be there doing whatever he does in Suicide Squad. Beyond that, it's certainly not out of character for The Joker to have henchman working for him, or people he pays to help him get what he wants. Even that, enlisting and/or paying people to aid him in his criminal endeavors could fall into the category of illegal business. It shows that there is some level of structure and planning that sometimes goes into The Joker's crimes and endeavors (whatever they may be), that The Joker isn't always just some lone wolf who runs around randomly/spontaneously doing what he wants, and Leto's version seems to be an extension of that idea.