You phrase this as a general moral objection, but I'm curious to know where the heart of it lies.
I stated that no (meaning "almost no") libertarians think that a government mandated retirement system like Social Security or a health system like ACA is a valid function of government. The primary objection is that the action of government is definitionally force, and this force is applied in an act of aggression (to make you do things that you prefer not to do). That's generally objectionable.
I think many of the non-anarcho-cap libertarians would accept the notion of public criminal courts and perhaps police, and a defensive military, and taxing for these sorts of common good features is perhaps the upper bound intrusiveness that should be accepted. This relates to the US Constutional issue of "general welfare". The term means activities that benefit all similarly (not necessarily equally), as opposed to activities that benefit individuals or select groups. So draining the swamp to eliminate malaria mosquitos is a general good. Treating the group that has already contracted malaria is a specific benefit, not general. Improving roads benefit even those who never travel - a general good; subsidizing fuel ethanol production and not say clean coal or others is not a general good.
Is it that money is being taken from you and put toward something that does not directly benefit you?
It doesn't matter at all whether it benefits me or not. The government takes my money by taxation(force) and then uses the money for things that I don't choose. Who gives then the right ? Where does this government get the right to interfere with my property and my choices ? It's a violation of the social contract.
Consider social security taxes. The do-gooders BELEIVE that's in my best interest. But say I could use my own money to start/expand a business or further my education and therefore be more productive and not need this socialistic system ? Or say I use the money to buy jelly donuts and a bigger screen TV - and then I can act as a object lessor for others of how not to live. Or say I know that my family history or chronic diseases mean that I am unlikely to ever collect social security.
Applying a one-size-fits-all policy by force necessarily creates lower economic efficiency than 300million ppl making their own choices. I have no objection at all to someone creating a PRIVATE social-security type system, and I might even pay the dues to join myself, but it's truly obnoxious for others to dictate how I must live when I am not causing any harm. They aggress against me without cause.
Is it that the money is going to someone who did nothing to deserve it?
I'm in favor of personal charity which is a transfer of weath to those who didn't earn it.
But "deserve" is a weasel-word you'll need to define carefully before I'll address that.
Is it that you see it as a losing value proposition - society wasting money by "propping up" an aspect of itself that should be left to adapt or die?
Economically it IS provable inefficient (a losing value proposition); that's not even a serious question.
I'm not suggestion you are going there but a lot of Lib/Progressives who can't offer a serious economic counter-argument spew a form of denigration/ad-hom fallacy along the lines "anyone who doesn't agree with my redistributionist idea wants to kick the crutch out from Tiny Tim". No it's not "adapt or die", except within the limited domain of economic competition where we should all rationally want efficient markets and efficient use of resources.
The libertarian objection is that schemes like social security or ACA is an application of government FORCE as they expropriate personal property for ends that are not the preference of the individual (violates the non-aggression principle). The Constitutional objections are that these programs are not in the "general good" but designed toward the specific good; perhaps others.
The economic objections are manifold. / Any "central planning" program is necessarily inefficient for several reasons; the unified plan&policy can't apply well to the needs of a diverse population. Further the diverse population does not have a single unified "goal" wrt health or retirement. Few people are getting what they prefer; and few people prefer what they get. / For some reason that isn't exactly clear (probably relates to the size of the nation, the diverse population and therefore lack of altruism across groups), the US government programs generally have very high overhead and losses to fraud, abuse and waste. / Because the government is involved crony capitalism often results. We can easily see this in DoD companies, but it applies to insurers and health care & service providers as well. / Because this is US government there is little financial responsibility in the programs. Social Security pays out more than is actuarial sound. No private insurer - not even a charitable non-profit with donated overhead could run social security as it is currently run (the SS tax is too low), BUT no politician is willing to correct this massive flaw. IOW the fiscal decisions are based on politics and pandering to voters or donors - not rational consideration.
The impact of any redistribution program (and that includes SS & ACA) is to reduce the marginal advantage of working&producing. So on the edges some ppl are induced to retire or take disability rather than work, or to work less to qualify for ACA subsidies.
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My moral objections are also manifold.
These plans are forced on me despite my will and preferences. It's slavery to take the product of my work for ends that I don't prefer.
These plans are an imposition on individual choice by creating terrible motivations to interfere in the lives of others. Let's say the government experts declare that saturated fats and excess salt in your diet are bad (as they did). The existence of a central health system should cause central planners to want to reduce systemic costs by imposing taxes (or other forms of force) against consumption saturate fats and salt. However recent finding (see the "Cochare Review" for details) show that saturated fats and salt aren't bad as previously thought. We are all forced into acceding to the decisions of a central planner - even if we disagree, even if we prefer otherwise, even if these decisions ultimately harm us. It's a massive inducement for totalitarian thinking and losses of personal liberty.
I suggest you examine the war on fatties that the Left is 'genning up. It's become an afterthought in news articles to include words about how much extra HC is needed by the obese. If people want to over-eat of be obese - it's their personal choice and business. At least it should be their personal business, except that we are forced into a public health scheme that we all pay for - thus creating a motive to tell others how to live (which I find obnoxious).
This sort of tyranny of the majority government now extends into the most intimate parts of life - where government has no valid business.