My dad is in his 60s, started his company with some friends in the 90s. None of them got super rich, but they are all doing well, and all slowly going into pens

My dad is in his 60s, started his company with some friends in the 90s. None of them got super rich, but they are all doing well, and all slowly going into pension. The company grew to a mid-size level, but actually most of the early employees stayed, and I think the average tenure is still probably > 10 years. Switching jobs every 3 years is weird, it is pretty much the time it takes to learn the ins and outs deeply enough to be an expert. There's some sense to it, as after learning all you can, it might be better for your career to search for new challenges. There's also the nonsense that switching that often generally yields significantly higher pay.