That's just a lie. Ah, the beautiful false equivalence... you will be nothing in 100 years, but you're something now. You can choose to be nothing now as well if you want, except that you're not, because you're something while you're here.
You've been given about a half-century on this planet; you're one of the luckiest groups of atoms in the entire universe to have agglomerated into a self-replicating sentient body that is on the brink of voluntarily expanding into a next level of its evolution at a more and more rapid pace.
At the end of the next century, the human race will probably be, as a whole, more aware and more advanced than ever before. And you, of all the agglomerations of atoms in the universe, get to be a part of it. You get to contribute; you get to be a cell in this incredible human race. And even better, you get to exist at a time when all the humans on earth are connecting to each other and spreading information and knowledge faster and better than ever before. We're becoming a human organism, we're cells in a great life-form, neurons in a giant brain; we're going to evolve as a planet now, faster than biology could ever dream.
Happiness is love, and love is the glue that binds us together like neurons, each knowing if only instinctively how important the others are to the great network we're in. You can isolate yourself and think that you don't matter and everything is futile, but if you do that, then and only then will everything actually be futile. Otherwise, you are very real, the time you have is real, your life is real, what you choose to do with it is real, and the results will—in some small or maybe big way—evolve the human race.
To me, that matters.