Your best chance at doing great things is to be totally undeterred by other people's false confidence. Your colleague? They have no idea. Your boss? Guessing, doing their best. Your bosses bosses boss? Thinks they need to know, wants you to think they do, actually doesn't.
Of course people build expertise, talent, and wisdom. But we're all in the same boat. There's no special sauce, no secret they have that you don't. This is a mantra to set you squarely on your feet each day. Remind yourself of these things and you'll be more effective and happy, whether you're just starting out or you're running the show.
If no one knows what they're doing, then you're at least as well equipped as anyone else. Most people think doing a good job or being a leader means projecting certainty and exuding confidence. The next time you encounter that person, remember that they have no idea what they're doing. No matter how confident they seem.
Since no one has any idea what they're doing, the best of us have an obligation to keep learning. Your experience and knowledge matter, even though you may never know the answers. Good news! You don't have to know the answer, you just have to know how to find one.
People with power and privilege start to believe their own hype. Never be that person. No matter what you know, in the grand scheme of things you don't know shit. It turns out you can be visionary and decisive and collaborative and humble all at the same time, it's just hard. But all the best things are hard.