Space is big. Really big. You just won’t believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.
Douglas Adams wrote in the notes accompanying the published volume of original radio scripts that he wanted Slartibartfast's name to sound very rude, but still actually be broadcastable. He therefore started with the name "Phartiphukborlz", and changed bits of it until it would be acceptable to the BBC.
First guy is saying, "there's no point in trying to figure out the "answer to the universe", it's a lot easier to be happy if you just go with the flow".
This leads the reader to assume that he's got it all figured out and is a relatively happy guy, an assumption that is subverted when asked plainly, "are you happy?"
I don't know that there's a specific take away here, so much as it just being a funny quip in a larger exchange.