I never wholeheartedly disagreed with him per se, it was the manner in which he said it. No one living on planet earth believes humanity, and life itself, is without problems.
But like you said, he doesn't offer any solutions, just stating the issues. And here's why I can relate to him:
I used to think like him. I used to be a complete pessimist and wondered why we even exist at all. He then goes on to claim that we try to justify our existence with our pleasures. This is where I disagree. I'm sort of a hedonist in a way. If things in life give you pleasure, joy, satisfaction, whether it be an accomplishment out of struggle, a cigarette, an orgasm, a cupcake, or marijuana, it doesn't matter. The sheer fact that things give us pleasure make life worth living and makes the whole process WORTH repeating.
In other words, been there, done that. I've been at the mountain top ready to jump off, I've been in the bar drinking 13 beers and crying to myself.
What I realized is that even though life is pretty much superficial and pointless to a large degree, there is still SOME good in it, or at least there are parts in it that outweigh what is bad.
He's probably had some major existential epiphany where he must come to grips with the meaning of his own life, but can't find it, so he's using his negative emotions to cloud his judgement over what is a completely neutral thing: life.
Life is what we make of it. It's up to US to make it good and worth doing. It's our responsibility.