How is society supposed to function without an underclass of poor and unhealthy wage slaves?

Yeah! Who's gonna deliver my groceries?!

I recommend Neal Stephenson's Snow Crash ... tl;dr: guys with katanas and kids on skateboards with really cool tires and grappling hooks ^^

that's exactly how! self-interest. being lazy is always up there as an option. some people button-mash that shit the minute they wake up. and not all of them are poor, unhappy, unhealthy. it's usually only when other people feel the need to remind them that they can press pause and the check the list of available commands to which they usually answer something like: "no shit, sherlock", that they suddenly feel inadequate and stressed.