Why do people want to know so much about life if in the end we're all going to die anyways?

Your question seems to assume that things can't have value if they're temporary. But we care what happens today even though today will end in a few hours. This is because one important source of value is what we experience: it matters to us to avoid pain, to enjoy the lives we live. That's a good reason to find out about life even though life won't last forever. It may also be that some things gain in value by being temporary: we might not find rainbows so beautiful if they were in the sky permanently.