Ask HN: What was your most humbling learning moment?

I've worked on large products for large and small companies and written tens of thousands of lines of code across my career, solving complex, abstract, challenging technical problems in a variety of languages on a variety of platforms, sometimes under difficult conditions. I have often been a resource for my friends and co-workers when they have programming or technical questions.

I only recently learned how to correctly raise and lower window blinds--I had been doing it wrong my entire life. It was maybe the dumbest I have ever felt, and was a humbling reminder of how much I don't know about how much I don't know.

Have you had similar experiences?