To be a successful leader you must have integrity. If there are cracks in your foundation you won’t last long. The higher and longer you build, the wider those cracks become until they are glaringly apparent to you and everyone else. A small inconsistency or underhanded behavior will become a massive issue as others are now scrutinizing your actions and mimicking your behavior.
Those you lead will only follow if they trust and respect you. If you lack integrity, you will quickly lose the trust of your followers and then you will lose them. If there's no one left to lead, you're no longer a leader.