You need to consider most of the doubters have never done anything close to what he did, never hung a bulb vertically once in their lives and are, in general, absolutely completely talking out of their asshole.
His grow isn't that hard to build. You can make a vertical system that fills an entire room for probably around what he paid to make his - the trick is to use a laser level, 2x4's and corrugated pipe. The corrugated pipe is cheaper than PVC, but more importantly, it bends. You don't need any fittings, you lay it on a 2 by 4 and use copious amounts of electrical tape to shape it.