Unlike the case of building an airplane, when you’re developing software you don’t know when you start sometimes if you want to build an airplane or a helicopter, or even if you want to fly, or indeed, if you’re building a vehicle of any kind, and not some kind of corn mill or a movie theater, perhaps.
The thing about software, indeed, most of it isn't space shuttles or life support systems. But it can go from paper airplanes to model airplanes to real airplanes more quickly than you'd think. Your hobby website could take-off to be an income and then a company and have leftover code all around.
It does usually go from paper airplanes, to model airplanes, to real airplanes. But if you set out to build a real airplane, you'd probably end up with a train.
