If nothing is backing it up then it has no value.
True, but nothing in this world has intrinsic value (except maybe morals lol), even food's value is relative. Look at gold, it might have properties which make it appealing, conductivity, corrosion resistance, etc. But if we found a both better and cheaper alternative for each of its uses (composite materials ¿?) then it would lose most of its value, value is relative to the dependance on something (aside from demand and supply), if people depend on Bitcoin for its convenience, it will have adhered value, but nothing, no vow, no word, promise, or bond ever had any intrinsic value no matter where or who it came from, if it did, we wouldn't need divorce attorneys now would we? ;)
Yet who are we to judge if the always epic BakaBT has now deferred to the less mighty Bitcoin :P