Earlier quoted context omitted.
I'll never understand why this keeps coming up. Energy consumption is not a waste if it has utility, and the bitcoin network has utility. I suppose you could make this argument for some worthless altcoins, but the difficulty for those is low enough that the amount of energy consumed is negligible.
Bitcoin is as worthy as tulips, in terms of intrinsic value. (Of course the worth of paper currency is the same, still, the backing is stronger) What will happen when bitcoins are worth less than the cost to mine them is anyone's guess
Now think of how much energy is "wasted" keeping all those accounts updated, the lights on at all the branch offices, etc.