The '90's animated Superman show had Lex as a genius Mafia type.
He was smart enough that he could have been real rich completely legitimately. But he's ruthless enough to kill for advantage or pride. And like Mafia types, he likes to keep a good public image. So he makes legit money, augmented by some illegal action on the side. He's got many points of contention against Superman over time, including his displacement as Metropolis' favourite son, Supes interference in his rackets, and a point of pride on being a self-made man, rather than an alien freak.
I suggest checking out "World's Finest", a Batman/ Superman 2-parter from the '90s.
Harley: "You aren't going to kill us, are you?"
Lex: "No. I abhor violence...... Mercy will." (Mercy is Lex's bodyguard and driver, occasionally assassin)
New Lex:
Lex was a gang-banger growing up, much smarter than average, created new designer drugs, pioneered ingenious smuggling methods, ran numbers rackets, did some computer hacking, and was socially intelligent enough to move up the ranks without getting shot. He gets busted, serves his time with good behaviour, and emerges as a changed man, legal, self-made entrepreneur, and favourite son of Metropolis with a great redemption story of bad kid gone good. Except he didn't go good, he just got more careful. All his time in prison, he was establishing connections, granting favours and developing new toys and drugs. Hell, maybe it was his plan all along!
I see the performance as layered. He'd have to be slick and charming enough that society at large sees him as a good guy, but occasionally show the audience that calculated cold-blooded willingness to slit a throat (or have someone else do it) to satisfy his greed or pride.