Houses are sometimes built like that, but I've seen indie builders just build the house, rent it out, and then sell it. There are multiple ways to build and sell a house.

Writing code that's maintainable, secure, and performs well isn't all that difficult, and it's certainly not some horrible burden that will eat up all your time at the expensive of customer acquisition. There's no excuse for sloppy work, and yes, customers can jump ship if they think your product is substandard and response time adds to that feel.

You're also not going to be less busy in the future and having a codebase that's difficult to maintain is going to put excessive pressure on you or your team. Sloppy code is harder and more expensive to debug than well written code in all respects. You're also more likely to have major problems (performance, security, grim bugs) that could have been avoided simply by thinking a little up front. It's not all that much more expensive to write decent code. It's also not appreciably more time consuming to write a decent NodeJS app than it is to write a Rails or Django app.

I strongly suspect you're conflating over-engineering with making wise decisions that don't require a huge time burden and make life easier in the long run.