We might wonder if socialists actually think socialism (as characterized by invasions of private property in the form of taxes, regulations, price-controls, or nationalization, etc.) can create more wealth and prosperity than capitalism (as characterized by private ownership of property, the factors of production, and the accumulation and investment of capital for the production of even more consumer goods, etc), or if they're actually primitivists who hate wealth and want to restore humanity to a standard of subsistence living.
Perhaps they have backed out on this argument of wealth-creating socialism, instead opting to attempt the case that it's "more equal" or "fair?"
Never mind that equality is an end that can't be achievable, and is contrary to human nature; they don't believe in equality anyway. Equality is not where all men are equal, i.e., no one is a tax-payer. Their standard of "fairness", if they even have a criteria at all, is apparently that of income. But who are they to determine the subjectivity of wealth?
We can also look to the simple fact that the term "the 1%" arose under the biggest State the world has ever seen to refute their case that capitalism causes inequality. The reason they derive this conclusion is because they think America is the bastion of capitalism in the world.
This drastic inequality, addressed correctly enough by the socialists, is not a feature of the capitalism that we don't have, though. Capitalism, again, is when there is private ownership in the factors of production, i.e., when there isn't a State to infringe upon the private property rights of individuals.
To answer the question, I imagine the honest ones might admit that indeed they've recognized the preceding relative capitalism in America produced too much wealth (and a "consumerist culture") and that it's precisely that they know socialism is a means of destroying it that they advocate for it. They just, unfortunately for all of us, cannot see that the statism we have now is how it must be; there's no other way; this is what big government has to be like.
So, since socialism causes us relative poverty than that of not having it, it should be defended that socialism is not the means of civilizing people, as the statists who support it often claim. Socialism makes us poorer, and therefore it's capitalism, and anarchism, that is the ideology of order and prosperity.
Against those who assert that anarchism would be a reversal in our progress, it's statism that has actually led to our decline. The closer taxes creep toward an intolerable amount, then the quicker humanity could be expedited to barbarism. All it would necessarily take is for the people to starve for their to be revolution against the criminals calling themselves "the U.S. Government." So they keep us fed - mostly with propaganda.