Mastery was not the term I was looking for. Competence is a better term. The goal of ERE is not mastery, it is competence. This competence is somewhat externally imposed, but it's imposed by reality. You can be internally motivated but not to the detriment of reality.
Consider a stone-age person. This person must have certain competences in order to live, like how to hunt, how to butcher, which fruits are edible, which are poisonous, which are healing, how to start a fire, how to build a hut, how to fight, how to sing and dance, how to make clothes, how to walk and run,... A stone-ager can be internally motivated, but is also externally compelled to survive. We're no different.
By no means do all these need to be mastered. Only competence is required.
Now insert our modern economic/educational system into the stone age world. So we have a person who spends the first 20 years of his life learning not all of those skills but rather training to do just one of those skills full time leaving little for everything else, both in time and skill. The purpose is that practicing this one skill will earn money (or sea shells) and this can be used to pay for everything else. Suppose this person is a healer but doesn't wanna anymore.
The healer can pursue two different strategies
1) Use his healer function to accumulate a tremendous amount of seashells. Increase the speed of accumulation by eating less, wearing less clothes, ...
This is the savings/sacrifice method.
2) Begin to develop the other competences necessary for his world. This will reduce his need for sea shells and over time allow him to spend less time healing. The sea shell accumulation will then be incidental.
Comparative advantage is often brought up as the reason why the first strategy is better. I'll bring of the law of diminishing returns, why the second method is better [for most people].
Lets grade competence
-2: Totally useless. Knows nothing. Must hire a certified professional to do work. Certification is necessary because I don't know how to evaluate the work. Because of this I must pay a lot of money.
-1: Informed customer. Knows how to evaluate, but not how to do. Can hire an amateur or an apprentice because skill can be evaluated. Can say no to unnecessary professional procedures. This costs less.
0: Self-sufficient. Can do an okay job. Does not need to hire. Free.
+1: Dilettante. Can do a better than okay job. Informed customers will hire as will the self-sufficient when they want a better job. Can also work as a prepper for professionals to refine. Can sell stuff on etsy. Side-income. Gets paid a little money.
+2: Professional. Works full time. Is paid a lot.
In general, people are now brought up to be a +2 in a single field and be a -2 in everything else. Therefore, strategy 1 is a natural way out of work. They'll sacrifice, accumulate money, and then hand that money over to investments, something which they also know little about.
The problem with specialization is that while you as a professional get paid a lot for +2, you'll also be overpaying other professionals a lot for -2. E.g. paying $15 to fix a flat tire; something that with reasonable practice takes 10 minutes. That's $90/hour. Getting your tax return done professionally can easily be upwards of $200/hour. Do you make that much?
The ERE strategy is more like strategy 2. Develop 20th century life skills instead of stone age skills. But prioritize life-skills rather than random "passions". Cooking is a life-skill. RC planes or violin playing is not, really. Take all those neglected skills to level -1 if you hate them, 0 if they're okay. +1 if you have an interest. +2 if you're passionate about them.
Then you pay others only to compensate for personal incompetence when such competence is not worthwhile. (This is where the law of diminishing returns enter.) For example, you pay the +2 bike mechanic to thread the headset for you. You pay the +1 hobbyist change the shifter cables and regrease the hub bearings. You adjust the brake cables and the saddle yourself. Strategy 1 would be to pay +2 prices for all of these.
I agree that mastery pursuits are asynchronous. However, competence pursuits are not. They are, in fact, rather synergetic. Competence in one field will make it much easier to gain competence in similar fields. Building on that will make every new addition easier and easier.
In conclusion, if your competences look like this (+2,-2,-2,-2, ...., -2) and most people have be raised this way, I think there's a tendency to focus on FI and sacrifice as a way of speeding up FI. Once FI, your competences will still look like (+2,-2,-2,.......-2) and so if done this way you still worry about your investments.
However, with ERE your competences will look like this (+2,+1,+1,+1,0,0,0,0,0,0,0,0,-1,-1,-1), the whole idea of FI and saving a lot of money becomes almost irrelevant because you can now make money almost at will and ironically you don't really need [much of] it.
In my opinion, perhaps due to my INTJ competence-striving temperament, I find strategy 2 to be much more fun than strategy 1. Strategy 1 would almost feel like a prison sentence counting down the days until the release date of the crossover point is reached. And then what ...
