Manufacturing Fiat wastes more energy, incredibly more (i have answered this kind of threats three or four times). But if you are really worried about it, perhaps in a few years more efficient and cheap mining hardware will be arrived...
It totally doesn't matter how efficient or affordable mining hardware is. We could power the whole network with a handful USB miners. It's the difficulty of scaling up a mining operation that makes the hash power rare, and thus a legitimate factor of gauging your commitment (which therefore can't be arbitrarily high). That's the core of the proof of work principle that makes bitcoin's distributed consensus possible.
