I’ve had the honor and pleasure of mentoring a few very bright & ambitious younger professionals in the past few years (something I recommend everyone 35-65 do at least once).
Most of the mentoring comes in the form of “These are the details of a colossal and very expensive mistake I made when I was age [their age]. This is exactly what it cost me, both monetarily and professionally. My motivations in revealing my most embarrassing vocational cockups to you, in hopes someone else can learn from my errors secondhand without paying the price I did. I’m not saying you will make zero mistakes in your career, but at least you can avoid mine, or make a better class of errors.”
If you aren’t leveling up every few months, you’re stalling out. And you will be ultimately beaten/out-earned/out-promoted by a harder/smarter-working same-age peer who are making better choices than you.
At age 23, it’s hard to distinguish between two high-IQ individuals with different levels of discipline/work-ethic/conscientiousness. Over the timeline of decade or so, the compounding difference between those who made hundreds of correct, difficult-and-self-investing decisions, and those who’ve made hundreds of easy (at the time)/self-limiting decisions becomes rather stark.