Worth? To who? Life, objectively speaking, is worth exactly the same now as it always has been: Nothing. Everything. With it, existence is filled with chaos, creativity, emotion, adventure, fear, joy, horror, lust, kindness, logic, art, macaroni and cheese, and Tom Selleck's mustache. Without it, existence is just a bunch of stuff, psychotic and pointless little atoms bouncing and spinning around in each other's gravity until they run out of energy and stop.
A meaningless answer, for a meaningless question.
Although even that is a better query than your friend's second question. 'Name the last person who died that was celebrated for the things s/he did for the world'? Pretty sure if he wants gravitas, there's probably a list of recently deceased Nobel Prize winners out there or something that will shut him up. But frankly, that strikes me as a rather juvenile question, to be honest. It seems selfish, and thoughtless, and needlessly confrontational. The World is a cold, cruel, and uncaring place, and I can't think of anyone who's ever done anything for 'it'. People who do things 'worth celebrating' do them for the ones they love, because they want to make the World a better place for those they care for. That is their
world, and it's the only one that matters, because it matters to them
. If I perfected cold fusion tomorrow, I wouldn't be doing it for 'the World'. I'd be doing it because the technology could benefit my family, my community, and myself. Everything else is just good, good gravy.
I think your answer to him was pretty spot on. It sounds to me like his angst engine is just running on overload. Tell him to dial it down a little, fix himself an ice cream sundae, go outside to look at the stars, and quit being an asshole. He'll thank you for it.