Warning! Major spoilers ahead for Batman/Superman #17!
Superman secretly kept Lois Lane from becoming a supervillain. Without the Man of Steel, the star reporter of the Daily Planet would have found herself on a very different path. Superman doesn't just regularly save her life; he has actually changed it for the better.
Lois Lane is Superman's main love interest. In some stories, such as Injustice: Gods Among Us, losing Lois Lane can cause Superman to turn into a dictator. This also occurred in "Brave New Metropolis," an episode of Superman: The Animated Series (1996). It is pretty clear that Lois has a big impact on the Man of Steel and his ability to be a hero long-term. However, less explored is the way that Superman's existence on Earth impacts Lois's life.
In Batman/Superman #17 by Gene Luen Yang and Ivan Reis, DC explores what the universe would be like if there were alternate realities where Batman and Superman never met. Generally, this concept opens up a lot of questions about what would happen if their worlds crossed or what their respective cities and neighboring cities would be like. On top of doing that, this issue also explores what Lois Lane's life is like if Superman never made it to Earth. It turns out that the Man of Steel has secretly been keeping Lois from turning into a supervillain all along.
After a version of Lois from a world without Batman falls into the reality where there is no Superman, Clark follows her. This results in not just the meeting of Batman and Superman and a merging of realities, but also an unexpected case of mistaken identity. Batman and Robin believe that Lois is a villainess known as Spider Lady. Spider Lady is the "Queen of the underworld" in the Metropolis of Batman's reality—complete with her own very feared gang. Metropolis has become what Gotham usually is and a large reason for that is the absence of Superman.
After a bombing at the Daily Planet, the Lois of Batman's reality spent time recovering before eventually faking her own death. Later, she became Spider Lady—though she may not be quite as bad as she seems. However, generally it does seem that without Superman to save the day in Metropolis, Lois Lane became a sort of kingpin of crime, as well as a casino owner. Her identity is often firmly rooted in her drive to expose criminals and wrongdoings through journalism, so the fact that Lois' entire career trajectory changes so drastically is rather shocking.
Though she's perceived as a criminal who has her headquarters at the former Daily Planet—aptly named the Spider's Nest—this alternate Lois actually isn't shown as being very evil. In fact, she actually tries to help Superman and Lois find out what is happening. Superman and Batman now have to save a new world, without knowing what they're getting into. It could always be assumed that if Superman failed to save Lois, she would die and he would be negatively impacted to various degrees. As mentioned previously, this has already been explored and commonly results in Superman becoming a dictator or fascist figure. Interestingly enough, Lois also would have turned into a figure who produced fear and who lived in a way that is far more negative. The two are affected almost the same way, just with different outcomes that are likely a result of the difference in available power and influence. Thanks to Superman's existence, Lois Lane as fans know her, is not a supervillain.