The "changing the world" talk is just as hollow as corporate business talk. Just a way to talk about what you're doing without specifically mentioning that "we're doing this to get more money", which is the actual reason anyone ever does anything.

Some founders/investors believe their own BS because that's what a good salesman does.

Being practical and sugar coating words has been the way to do business forever. The startup speak is just a specific flavor of words that's popular in a region/culture now, is representative of the business culture to some degree, but is just as hollow as any pleasantry.