Thats a fantastic question. Here's my take: https://news.ycombinator.com/item?id=47917314 - would love your thoughts on it.
In short, I think you're asking a billion dollar question - how do we solve the verification, validation, and QA bottleneck?
The way I handle it for my personal projects is I invest tremendous time and effort into writing thorough test and validation suites.
I bet the next billion dollar companies will be those addressing this verification, validation, and QA bottleneck.