The difference lies in what is necessary to live and work effectively and what is not. Unless I want to make myself irrelevant in society, which is an option some choose, I must work for a boss, I must buy or consume products from oil companies. Groceries must come from a capitalist endeavor. These are necessary and opting out of them almost always marginalizes someone to the point they they cannot contribute meaningfully to social change.
Surplus funds for retirement are different than day to day expenses. Pretending they are the same is not helpful. I know some on this list don't like the term surplus income but if one has income that is not needed to maintain day to day living expenses and one is free to choose to invest them or spend them on accumulating personal property it is surplus income. I have no metric to determine at what level income becomes surplus and I doubt one could be fabricated but this does not mean it doesn't exist. It is like pornography in that one knows it when they see it but an exacting definition is a bit slippery.
I realize these funds can't realistically be expected to be put in a shoebox under the bed but buying stock in Exxon or Costco or whatever does not see to me to be the answer. The best explanation I can come up with off the top of my head is in the form of an anology. One might oppose slavery and yet need to eat food produced by slaves in order to survive. That doesn't mean one is also free to own slaves and still claim to oppose slavery.
I teach my students with the frequent use of analogies and it's become a sort of default way of expressing myself these days. I'm reticent to use slavery in an anology almost as much as using Nazi's but it's late and I'm too tired to be more original than that.
John Thornton