I'm sure there are some people who would be okay with a barn so long as they had food, shelter, and warmth. But a large number--me included-- would throw a tantrum, start ranting and ****ing about how unfair everything is, etc. I don't think a lot of people want to admit that they would react as David did because he was such a prick in the series. Had he been more... human, I guess, then maybe people would be willing to say that they'd do the same. Of course, I'm talking about David's reaction to living in a barn--I'm not saying all of us would turn into murderers.
His going axe-crazy with the morphing ability is pretty much the old "with great power comes great responsibility" bit. And, again, I think a lot of people would be very tempted to use their powers for personal gain--but hopefully not outright violence and identity theft.
The kid has a superiority complex, an ego in need of stroking, that was probably the result of his moving around so much.