The Master and The Mentor: Liberating The Learner and The Learned
The Master is like a knowledge miser, sitting on a pile of gold he can not spend. He is unhappy, alone, unable to help most people, and also wracked with "imposter syndrome" that nobody can cure him of since no one else knows enough to tell hem he's not an imposter.

The Master model doesn't work.
The Mentor model does.
The Master has to know everything. He will rarely use most of it, but by knowing more than anyone could catch up to learning, he cements his authority and his "right" to tell other people what to do. No one can challenge him since he is The Master, but he is also keenly aware of his shortcomings which he dare not talk about lest his master status be threatened.
He can also never transmit his entire body of knowledge to another, firstly because it would create a threat to his power and create a rival who will supplant him as he surpasses him in knowledge AND risks repudiating that core knowledge as the disciple continues growing. Now finally someone knows as much as he and is poised to question his authority. So his protégé is his biggest risk, but also the only solution to his solitude, because no one else can understand him. Betrayals abound in these situations.
Normal people never really learn from The Master. After all, he does know a LOT. But he can not go far enough down to others' level to really teach them the simple things they need to know. So he is mostly useless except to the protégés who are at the same time his greatest threat and his promise of salvation. But for normal people, his goal is authority: to tell them what they should do, not to drain away that authority by giving people his power, his knowledge.
In the end, The Master is like a knowledge miser, sitting on a pile of gold he can not spend. He is unhappy, alone, unable to help most people, and also wracked with "imposter syndrome" that nobody can cure him of since no one else knows enough to tell hem he's not an imposter. And worse, those same people who don't know what he knows - and whom he doesn't even respect anyway - adulate him, driving him further into his bubble, yet also giving him the praise he so badly needs (for all his sacrifices for the sake of higher knowledge). Yet that same praise rings empty, because they don't really know enough to have an opinion or what a fake he is anyway, and if he tells them, then he loses his authority and adulation just the same.
In fact, the imposter feeling will gnaw at him forever, since true mastery is actually the discovery that you don't really know anything. When you delve deeply enough into a topic, what becomes clear is how much you don't know. And yet, by reputation, you are The Master, so if you don't know, then who does? And if you don't know, then why should anyone listen to you anyway? Whence comes your authority?
So you are in a bind as The Master. The true humility of the sage is impossible since it would threaten your hermetic bubble of authority. And yet you can never learn enough to solve it: hence, the imposter.
The Mentor, on the other hand, doesn't need to know everything.
Like the man who doesn't need to outrun the bear (he just needs to outrun you!), he just needs to know more than the person he's mentoring.
A 6th grader could have a mentor in 8th grade. A billionaire CEO could have Jeff Bezos as a mentor. And in many cases, The Mentor only need be "ahead' in one specific area. They could fail at relationships, bowling, investing. . .but as long as they know more aboug glass blowing than a rank beginner, they can be a mentor. And then the mentee can move on with no hard feelings when he has surpassed The Mentor. No dramatic "overtaking," like the protégé.
The Mentor is secure in what he knows because - usually he knows it because he's done it. He is not pretending to know more than he does or even posture that he knows "everything." He knows more than the people he is mentoring, whoever they are. That's it. And that's enough.
Now when a mentor imparts knowledge, he moves that 6th grader up to 8th grade, so to speak. He makes incremental changes (and sometimes larger ones) within the scope of their knowledge differential. So his teaching is effective, implementable, measurable, and accountable, since The Mentor is close enough to the mentee's level to adjudicate what is going on. There is no uncrossable gulf (as with The Master), since The Mentor is just a few steps ahead.
The Mentor is also sellable, unlike most Masters, who are too aloof to be sold in the first place. And also since you don't need 90% of what they are teaching, it isn't worth the money to pull him down off his pedestal to help you. Like cable TV, you just need one or two channels, not the whole library.
The Mentors, because they see progress in their students, are also fulfilled by their knowledge and their ability to help. There is far less ego investment, far les concern about legacy and transmitting your full body of knowledge to an "heir" or disciple who will undoubtedly disappoint you or betray you.
The Mentor's knowledge is only a part of his life, not his whole identity, because he is out there doing the things now that he is mentoring you about. His life is in flow, ease, and balance. He is entrepreneurial vs legacy focused. He is flexible, can always continue to grow and mentor new people, and doesn't get concerned that his knowledge base will become obsolete (along with himself), because he did not invest in the knowledge - rather he invested in his LIFE which brought him the knowledge as a side effect.
Then he gladly dispenses with it because his, admittedly smaller than The Master's, cup overfloweth. And he engenders gratitude in others, whom he can actually relate to, rather than leave in awe, which feeling leaves The Master alone with his inflated ego, which no one can really appreciate anyway except perhaps that one magic disciple, who again will probably betray him in the end anyway.
So The Master model is an antiquated failure, a holdover from European centralization of power and expert worship. The Mentor model is American, modern, infinitely flexible, and perfectly practical. Like American capitalism in general, it works for dumb people and smart people alike - but usually better for just ordinary people (which is why most Masters hate it).
The Mentor Model should be the measure of our future experts: to live first and then mentor those in their immediate wake, and in doing so, to pull the whole human race up one step at a time in the most efficient, proven, and fun way possible into heights well beyond what any Master could do on his own.
Addendum: A Quasi Defense of the Notorious "20 Year Old Life Coach."
In general - in general - the criticisms for these inexperienced theoreticizing neophytes are apt and just. These people are generally parroting something they've read but never experienced or tested. And they don't have enough hard earned wisdom to know bullshit when it is spraying in their faces. True.
But youth alone - and certainly outside of the narrow field of "life" coaching - is not a disqualifier from being a mentor - and a good one at that. Think again of the 8th grader showing the 6th grader the ropes of which is the best water fountain at school, when the library is the quietest, or how to sneak an extra slice of pizza from the lunch lady. Hardly life mastery stuff, but it is exactly 2 steps ahead of where the "mentee" is. And in general, the limited scope of the "coaching" makes it a relatively harmless endeavor even if it misses some salient details like how not to get bullied on the way to the school bus.
The Mentor Model is FLEXIBLE. It is undefined. It is circumstance based and of whatever scope you want it to be. There is no abstract and incalculable knowledge base that a great master deigns to share with your ignorant self. No, it is practical and easy to move on from without drama, entanglements, and protestations of honor and loyalty. Easy.
So even a 20 year old idiot can do it. In fact, when it comes to "modern life," TikTok, pop music, social media marketing trends and the like, these children can be extraordinary mentors to old geezers in their 40s who don't have time not to be clueless about important trends. They are at least 2 steps ahead, and that's exactly where they need to be.
So be kind to your more ignorant and inexperienced "coaches." They may not know about the grand concept we call life, but that doesn't mean they can't be fantastic mentors about all sorts of other things. And who knows. . . depending on what's going on in your life, they may be a couple steps ahead of you too. . .