Sure, you can say epistemologically that *nothing* is real …

Sure, you can say epistemologically that *nothing* is real unless there is an observer, too. Or nothing has a 'nature' that is concrete. But that's just a weird form of nihilism + egoism.

You can't act like that in the real world where things are happening, you are making choices that involve other moral free agents, because that's an irrational belief. And our brains are hard wired to deal in things' 'nature'; archetypes resound with the deepest parts of us like a gong. There is something to all that.