Inventing a product from nothing is hard.
Though you certainly can draw inspiration from existing things, maturing the idea into being often involves a painful process of trial and error.
You spend days building the product's core, only to realize that you should have done it another way. So, you delete some code or throw the sculpted piece of wood you spent so much time on in the garbage. And start over.
It is hard to destroy whether you feel an attachment to this thing you've made or not. You spent your precious time on it, and rebuilding will make the whole schedule slide.
I feel frustrated when this happens. And from experience, errors like these are unavoidable no matter how much planning you do ahead of creating.
Because they are part of the exploration process; they are part of the work.