Is it common to build a prototype to throw away, and then actually throw it away and build the "real" thing? I've never seen that, ever, in 20+ years of software work. The prototype ends up being the long-term production version, for all its faults and weaknesses.

I don't think so sadly, even an iron willed CTO will have to risk a lot of c-level trust to justify rewriting something "that works" (at first glance).

The artificial distinction between a prototype and a production system rarely survives reality in my experience. But that doesn't matter because the situation with long-term maintenance is not so different with freelancers doing the development to what you'd have to do with an in-house team.

It's rare for anyone to be around to look after the code they write for you forever. Ironically you might have more chance of a good long-term relationship with some of your freelancers - having a few good clients who come back to you from time to time is an excellent strategy as a freelancer.

So you always need the system and processes to be designed with future maintainability by other people in mind. Good developers will do that whether they're employed or freelance. Bad developers will mess it up either way too. Choose the people you work with wisely and try to make sure when you do bring in new people they have a good way to get up to speed so they can naturally take over as others leave. There's not much else you can really do.

Not my experience: freelancers have often built the initial versions of a product that have then become the permanent version. Even products that start as prototypes, if not total trash, often end up evolving into real software projects.

Why throw away software when you can iteratively improve and build on it? Unless the tech stack was wrong.