Just in general, we should never stop learning, improving, and trying to grow for our entire lives.
Specific to poker... no human being will ever "know it all". Poker is a game of adjustment to table conditions, so it is essentially "built into the game"... some call this concept the "metagame", and it is what makes poker so fascinating.
The metagame occurs when player begin to adopt a particular "hot" or "popular" strategy... this then creates opportunity for other intelligent players to devise a "counter-strategy" to take advantage of the popular strategy... eventually, players catch on and begin to adapt their popular strategy to reflect the adjustment... but then this allows other intelligent players to once again "get ahead of the curve" and adjust to the adjustment... and this process NEVER ends, it will continue until the end of time, because poker will never be a "solved" game, it is a game of incomplete information and there are just too many opportunities for +EV adjustments to be made.
I know many think "Game Theory Optimal" strategy is the end of this process, and perhaps it would be if players played perfectly... a very very small percentage of player MIGHT approach perfect GTO strategy, but the vast majority of poker players will never come close to GTO, because humans are not perfect robots, we are imperfect (and its not even close). The opposite of "GTO play" is "Exploitative play", and explotative will always be more profitable than GTO at any level of the game outside of the top 1% played at the highest stakes. Most of us won't ever get to that level, and that is why there will be proper adjustments to take advantage of the metagame until the end of time for almost all players.
My take on it, my opinions obv.