I think the answer is simple: those who “lose out” in a market economy would probably lose out even more in any alternative arrangement.
You might be tempted to dismiss my answer as some kind of simple right wing ideology (as opposed to a simple left wing ideology), but there are reasons behind my answer that I find compelling.
The first is empirical: we have lots of evidence of market economies, limited market economies, and non-market economies. Evidence suggests that the least well off are usually better off in a market economy. Data matters. But, correlation is not causation, so we must not rely too much on history.
The second is logical: economic theory, particularly that based on deductive logic, predicts that the least well off will be better off in a market economy. I can’t reproduce an entire introduction to economics in a single blog post, but with work, you can explore this and convince yourself. Don’t take my word for it!
In short, both logic and evidence say that the least well off fare best in a market economy. Those who prefer alternatives should be given a hearing, but they must bring logic and data, not just emotion.