Is it hostile to call an attitude pretentious? I don't think it is... Some attitudes are pretentious.

What is pretentious about the quote that started this thread is the apparent belief that the kinds of people that do the things we talk about and admire on this site - building new kinds of software, starting growth-focused companies - are the only people "that are interested in ideas and making new stuff". I agree that there is a fairly thin stream of the building-software / starting-companies hackers that you're thinking of, but I see huge numbers of people from all walks of life being interested in ideas and creating things. Artists, writers, journalists, directors, bureaucrats, other types of business people, on and on and on. I think it is pretentious to look down our noses at pursuits that are not our own, that's all.

Your comment about hackathon event planning is illustrative: hackathons are honestly not at all where I would go to find the highest concentration of people creating interesting new things.