In rockets, we have SpaceX. Commercial aviation has a higher regulatory barrier for entry, both in technical knowledge and facilities. You don't just spin up a gigantic, cavernous assembly line with thousands of technicians and billions of dollars in tooling overnight. I wouldn't be surprised if in 10-20 years though, someone backed by Google tried building a self-piloted, subsonic blended-wing-body 200-300 pax jetliner. Google right now has Kitty Hawk, but I think their ambitions are far greater.