Thanks for the responses so far. What actually prompted my post was this realization: a person who ERs is likely to pay fairly high payroll and income taxes for 10–15 years, but will then pay almost zero income or payroll taxes the rest of their life (let's limit the discussion to federal income and payroll taxes, while admitting that most people will pay state/local sales tax and property tax during retirement).
Public Finance economists have developed an elaborate way of judging tax policy called "optimal income tax theory." This was developed by James Mirrlees, who won the Nobel prize for this work, and many other scholars. I haven't looked at this stuff for a while, but let me try to summarize.
The problem: how to maximize social utility (well-being) through the tax and transfer system while distorting economic decisions as little as possible ("efficient"). People are assumed to have a declining marginal utility for money, such that an extra dollar for Warren Buffet brings him a lot less utility than an extra dollar for a Somali peasant. People are also assumed to have both different abilities (defined here to mean "ability to earn money in the labor market") and different income levels. The tax instrument assumed to be available is essentially a wage tax; capital transactions are not part of the earliest models for simplicity.
With these assumptions and a few others, you can, through a model, mathematically define the utility functions of everyone, and how the tax-and-transfer system would impact that utility. Solving the equation for how to maximize total utility is essentially an optimization problem (hence "optimal" income tax theory).
An interesting thing that comes out of this literature is that it would be great—if you are committed to maximizing utility at all costs—if we knew people's abilities, because if we did, we could just tax them based on ability, not on earned income. A tax on ability would be maximally efficient because it wouldn't lead to any disincentive to work the way that a tax on wages does, in the same way that a head tax is efficient. But a tax on ability is better than a head tax, because it allows for differentiation in tax burdens that many consider fair, whereas under a head tax everyone pays the same.
People that earn significantly less than their ability implies are called "shirkers" in the literature. They are seen as shirking their duty to earn money, which can then be taxed and redistributed to people with a higher marginal utility for a dollar. Shirkers decrease total utility at the expense of less able people. A Mustachian who retires early is the ultimate shirker under this worldview. Mustachians are high ability people who drop out of the labor force and drastically reduce their lifetime tax burden, while often drastically increasing their lifetime consumption of public benefits.
Personally I don't believe optimal income tax theory has much to offer real world policymakers, and I think many of its assumptions are unrealistic or at least incomplete. It just struck me that Mustachians, shirkers that they are or aspire to be, are the optimal income tax theorists' worst nightmare! But many prominent economists subscribe to the theory [see here for further reading: https://eml.berkeley.edu/~saez/piketty-saezNBER12handbook.pdf]. I say vive les shirkers!
Resurrecting an old (but very interesting discussion).
I am not sure you are reading the economic theories with the proper frame of reference. The expression you used: "duty to earn money", I believe, shows where you are thinking incorrectly!!
First: You are talking about "money" as if that is something concrete with real "marginal utility" in itself.
Money is a notional construct. It's simply an abstract promise to give some share of the future economy when you choose to spend it!! It is worthless outside the context of the society that makes that promise. It has been that way since the first caveman used a piece of shiny gold nugget to buy a wild boar carcass. The shiny metal nugget he handed had no "real" value outside the societal context, especially when technology had not yet developed to figure out the teensy weensy bit of industrial uses of Gold that exists today!!
When the value of "money" is derived from society itself, and its future ability to produce economic value, it follows that the said "society" can choose how to allocate that share such as to optimize that future production and economic activity. Tools available to do so include:
1. Redistribution in various forms (a "progressive tax system, "tithe" that is a social norm to the point of being a tax etc.).
2. Inflation - a highly inefficient and regressive tool.
Bottomline: if you are a true libertarian, you would engage no economic activity other than bartering. Anything else derives it's value from society and subject to change based on collective thinking.
Coming back to the "duty" bit - nobody has any "duty". I doubt any peer reviewed economics literature ascribes such loaded meanings. Can you pleas show me?
I would work if the marginal utility of the hours I spend gives me something in return whose marginal utility is higher. If not, as Homo Economicus and a newly minted Mustachian, I won't!!
Other points:
1. Asking for reorganization of how the future value of "promises" handed out already is not same as, nor incompatible with, tax optimization.
2. Redistribution is not stealing - unless you are a true libertarian who relies 100% on bartering and don't depend on society for anything. If you derived value from society, it follows you should pay for the maintenance costs of the said "society". When and if a billionaire complains about his 15% and lower tax rate, ask him exactly how much did he benefit from the social constructs like property rights, police, military etc.
3. Data seems to show that the American left wing politicians are far more fiscally responsible than the right wing. Simply look at the budget deficit numbers from the Republican vs Dem admins and you will see what I mean. Right-wing, starting with Nixon, invented the post-truth politics where we are supposed to focus on what they say, not what they do!!
4. Conserving the environment is not a liberal cause. Conserving is a conservative cause!! The politician with the biggest contribution to conservation in the US was a conservative - Teddy Roosevelt. Of course - we are not talking about the post-truth "conservative"s.
Not only do I not think that the liberal leaning Mustachians are NOT hypocrites, it seems self evident to me that any Mustachian who does not identify with the big-tent "liberal" policies in today's US politics are hypocrites!!