What about retirement? social security? disability? You might not be "making a living", but you are getting an income without working for it. Same for investing money. Really "working for it" is a loaded term in and of itself. You might be "working for it" by taking risk, or putting in labor. The author obviously doesn't think any investor is "working for it" by the the tone of the article, but this is precisely what retired america is doing?
"If you were raised to believe that work is the index of your value to society – as most of us were – would it feel like cheating to get something for nothing?"
I don't think this is the right question at all. People take for granted whatever they have, and likely may feel it's cheating, until they start taking it for granted.
I think the more interesting question is, if you could live even if society didn't value what you were doing, and you could do anything (even nothing) and still be provided with everything you need to survive - what would happen to individuals and what would happen to society?
People by nature I think are very externally motivated (society, wealth, materialism), and if you didn't make people go to work, would they? If they did, would they still put up with the crappy parts of it?
I think what defines a satisfied life is doing things that matter to you, make yourself work, try hard, think, make yourself smile a few years down the road (after you've forgotten the hard parts). But even when you have all the opportunity in the world, some people just procrastinate or fall off the wagon somewhere...