Requirements change over time. Domain understanding change over tim. Business change over time. Environments change over time. Unless you are a seer with perfect precognition, most of what you have done will be invalidated over time.
Hence: make your code and data easy to change, but simple, as you cannot predict in what way it will change.
Even then ain't nobody in a 10 person seed-stage startup got time, resources, or need to build the database you'll want to have when you're a 600 person Series C monster.
Hence: make your code and data easy to change, but simple, as you cannot predict in what way it will change.