The concept of "backing" is misplaced.
Commodities do not need to be "backed"... they are in and of themselves valuable because they are useful and scarce. Rice is not backed by anything. Gold is not backed by anything. Copper and pork bellies and sand... none of these are backed by anything. Yet they all have market values based on supply/demand.
Similarly, Bitcoin is a commodity. It is a "digital" commodity, true, but that doesn't make it any less "real" than any software. Photoshop is real. Firefox is real. The digital porn your have on your hard drive is real. (interestingly, it seems Bitcoin is the first true scarce digital commodity, because it can't be replicated by copy and pasting- it is genius for this reason alone if nothing else)
As a scarce commodity, Bitcoin doesn't need to be "backed" by anything. It is valuable as its own thing. Just as with gold and pork bellies, Bitcoin is valuable to the extent people want it.
Where "backing" is required is in a case such as paper money or any kind of "certificate." The paper, or certificate, itself is worthless. But, dollars had value originally because the paper was backed by a real commodity (gold or silver). It has value now because it's "backed" solely by the guns of the US Government. Citizens are forced to pay taxes in Dollars, and forced to accept dollars in trade. Sadly, it is violence and coercion that backs the USD now, instead of valuable metal. If dollars were not backed by the coercion of government, they would be worthless. Thus, their backing is necessary for their value. Not so for gold and butter and bitcoins.
So with Bitcoin, it doesn't need backing of any kind. The Bitcoin protocol is valuable as a commodity. If you think it's worth more than current market price, then buy it. If you think it's worth less, then don't buy it. But either way, don't spread the silly notion that it requires backing - and that the backing comes from "energy consumption" or "cryptography" or other such nonsense.
There is no backing for Bitcoin, and there needn't be.
Yes, well put. It really pisses me off whenever someone complains that bitcoin isn't "backed" by anything and gold is, for example. People often bring up physical industrial use-value as the thing "backing" precious metals. That's crap. The vast majority of the current market value of gold, platinum, even silver, is due to scarcity and other non-industrial-demand factors; the exact same factors that drive bitcoin. I'd further argue that bitcoin should be inherently more valuable due to its ease of transaction properties, but gold folks would counter that you can't physically hold it, so when the internet explodes you're f'ed. Fair point, but irrelevant due to really low probability.