This might be relevant to you:

> 56. Sometimes unsolvable questions like “what is my purpose?” and “why should I exist?” lose their force upon lifestyle fixes. In other words, seeing friends regularly and getting enough sleep can go a long way to solving existentialism.

True.

But might as well feel as good as practical, while you can. These don’t appear to hurt that. If anything they lead to more enjoyment of the limited time we have.

The advice is more aimed at people who think that human life has some kind of intrinsic value, I think. (Certainly that's one of the common LessWrong-o-sphere beliefs.)

> "None of this matters. In the end, you die"

People are born curious, and prefer pleasurable experiences to suffering. That's all it takes for something to matter, and it matters in the time before the end. People are what make things matter, maybe that's why the universe created some.