They may be far from having learned all their lessons in life--and hopefully are open to the wisdom of those with many more years in similar shoes--but that doesn't mean that can't have learned valuable lessons in ten, fifteen years of adult life. I know I have plenty of wisdom now that I wish I could have passed to a five-years younger version of myself. I don't think writing, sharing, or publicizing that sort of retrospective is necessarily presumptuous. Sometimes young tech personalities are pompous, but there are also plenty of my own peers (and juniors!) that I'm happy to take lessons from.

You learn extremely valuable lessons even during your traineeship. But it takes many more years to realize if that lesson is truly unique and worth sharing, and if it won’t be turned on its head as you learn more later in life.

I learned very different versions of the same lesson given 20 more years of experience. Sometimes just having my confidence in “old” life lessons shaken was a huge deal, it takes a lot to shake what I thought is bedrock.

If you watch 20 minutes from a 2h movie can you really tell something about the whole movie or just about its beginning?