If you consider the construction used primarily on-site materials, it appears the money largely went into laborer's hands. It's not like the region is teeming with employment opportunities for those folks, and they surely didn't just set fire to their compensation. My guess is it fed and housed a bunch of area families, not a total waste - but sure, the labor could have built something more useful.
Now the area is a national monument and will draw tourism, creating jobs and growing the economy in a desert.