The business section of any bookstore is full of leadership advice from successful people. What's missing is leadership advice from people who crashed and burned, which is actually more useful because there are more ways to fail than to succeed, and knowing what not to do is at least as valuable as knowing what to do.
The most common thing fired leaders say is "I had no idea there was a problem." This is never true. There was always a problem. People were just afraid to tell you about it because the last time someone brought up a problem, you reacted poorly. You didn't yell, maybe. But you got quiet. Or you asked a lot of pointed questions. Or you "noted it" in a way that made the noter feel noted. Creating an environment where people are afraid to bring bad news doesn't eliminate bad news. It eliminates your awareness of bad news, which is worse.
Leaders love talking about their "vision." A vision is an opinion that's been promoted above its station. It's what you think should happen, dressed up in language that makes it sound inevitable. "My vision for this company" means "what I personally want." That's fine, but own it. The moment you start believing your preferences are prophecy, you stop listening to people who see things differently, and those people are usually right about at least some things.
Culture is not perks. Culture is what happens when the CEO isn't in the room. If what happens when you're not in the room is everyone complaining about you, your culture is "mutual suffering," regardless of how many ping pong tables you bought. Good culture comes from treating people like adults, paying them fairly, and not making them attend mandatory fun events that are neither mandatory nor fun but somehow both.
The hardest lesson: the organization survived without you. It might even be doing better. Your irreplaceability was a story you told yourself to justify the hours, the stress, and the personality changes your family noticed but didn't mention. Everyone is replaceable. The question isn't whether you can be replaced but whether the replacement will make the same mistakes. Usually, they'll make different ones. Progress.