A lot of people seem to implicitly believe (or desperately want to believe) something to the effect of "the facts of the world make my value system convenient."
For example, anarchists tend to have a value system which says that hierarchies and systems of domination are inherently unethical. This is something I agree with very strongly, and is why I often describe myself as an anarchist. A common question then posed to anarchists is how, without hierarchy, bureaucracy, or other such systems of social control/management, it would be possible to achieve the large-scale coordination needed to accomplish certain tasks that are considered necessary for human flourishing: industrial-scale production of antibiotics and vaccines, management of carbon emissions, maintenance of a power grid, and basically anything else that requires a sustained, large-scale and legible set of social processes. Rather than addressing these (in my view) very valid concerns, most anarchists respond by dismissing the question. They claim, for example, that without capitalism we would have no need to manage carbon emissions, because the market incentives to emit would be gone. Or that industrial production of medical supplies isn't really necessary, because sufficient quantities could easily be made by small-scale local producers, etc.
And I'm always tempted to say "wow, how incredibly convenient". We don't even have enough understanding of human psychology to successfully model human behavior in our own society, and yet you're absolutely sure that in your hypothetical future society, humanity would just... no longer have any desire to engage in high-emission activities? You're absolutely sure that the physics and biology and chemistry and engineering involved in medical production all just happen to work out to make small-scale manufacture consistently doable? You're absolutely sure that all these problems people are posing just happen to be non-problems?
You may be right, certainly. It would be lovely if these things all worked out to be non-problems. But that's not something that can be determined through political theory. It's something that can only be determined through rigorous empirical study and technical work, and the conclusions that work comes to might just not turn out to be very convenient ones. This is why I sometimes don't call myself an anarchist.
But either way, my values stay unchanged. No matter what the answers to these technical questions are, I remain absolutely steadfast in my belief that systems of hierarchy and control are deeply unjust things. Either way, I will continue (as much as I can) to work towards a society in which these things can be done away with to the greatest degree possible, and their deleterious effects can be mitigated wherever they remain. And I think that I'm far more able to actually do that for being honest with myself about what the challenges of this project really are.
I want to be clear, this is not just a tendency I find with anarchists. I've encountered people of basically every political ideology engaging in this sort of dismissive optimism, insisting that the questions raised by their value system in fact demand no answers. But ultimately, it's not intellectually honest to insist that the universe has conspired to make your value system an easy one to hold. And that kind of intellectual dishonesty actually gets in the way of successfully working towards realization of the values you have.
Which is why, in my view, the most effective way to approach your social values is not as positions to be defended but as goals to be achieved. Inconvenient facts are not points against you, they are obstacles in your way. Perhaps they're insurmountable obstacles (that really would be, I think, a point against you), but perhaps they're not. The only way to find out is to acknowledge them as genuine obstacles and to try to find solutions. The inability to acknowledge the challenges in front of oneself has been the downfall of many, many movements, and the solution is as simple as having a little intellectual humility. And personally, I'd rather not let my ego get in the way of building a better world.