The following article contains spoilers from Action Comics #1053, on sale now from DC Comics.
Lex Luthor has never lacked pride, but Action Comics #1053 (by Phillip Kennedy Johnson, Rafa Sandoval, Matt Herms, and Dave Sharpe) takes this to an unprecedented degree. During the issue, following Metallo transforming the Blue Earth Movement, Superman visits Luthor to gain insight into his foe's strange behavior. During their conversation, Lex proclaims that had he been born with Superman's powers, he would have been "ten times" the hero he is.
It's a bold statement for sure, and one that Luthor and his pride undoubtedly believe. It is also categorically false. There have been instances where Luthor gains powers similar to Superman's or where he otherwise fills in for the Man of Steel. In the end, his ego always makes him squander these chances to do good. The fact that he can't recognize this proves that he is deeply deluded.
Lex Luthor Believes He Can do Better Than Superman
The most recent example of Lex filling Superman's shoes came during DC's Rebirth era. At its start, it was assumed that the New 52 version of Clark Kent had died, leaving the Earth without its greatest protector. Luthor, who by that point had been working more closely with the Justice League, developed his own Superman power suit that he used to become the new Man of Steel.
Naturally, most people rejected this silliness outright, and when the true Superman returned, Luthor found himself being pushed out of the spotlight. The mistrust and lack of appreciation he endured drove a wedge that ultimately caused him to make a deal with the dark goddess Perpetua, nearly destroying the entire multiverse in the process.
Even in other universes, Lex wastes the gifts that Superman has. The most famous instance is in All-Star Superman (by Grant Morrison, Frank Quitely, Jamie Grant, Phil Balsman, and Travis Lanham). To avoid the death sentence, Luthor gave himself a formula that temporarily granted him Superman's powers. In classic Luthor fashion, instead of using his powers for good, he went on a rampage throughout Metropolis to try and kill the Man of Steel. Only after the formula burned out did he realize what he could have accomplished with his gifts, but as always, his single-minded determination to be superior to everyone ruined whatever good he had to offer the world.
Lex Luthor Has Never Lived up to Superman's Values
At the end of the day, the main problem Lex Luthor has is his selfishness. Everything he had accomplished was done in a vain effort to prove that he knows best. His tactics directly contradict what makes the Man of Steel a hero, and history proves that he would abuse his powers every single chance he gets.
Lex Luthor is blinded by his inflated ego. He is typically the same arrogant man across any reality. He has had multiple opportunities to do good, even when he wasn't trying to earn the public's favor as a hero. With all his brilliance and resources, Luthor could have changed the world for the better in a hundred different ways by now, but his obsession with asserting dominance over Superman will always hold him back.