What you're describing is actually rational behavior. You're describing the difference between what you'll imagine beforehand makes more sense vs. what you know

What you're describing is actually rational behavior. You're describing the difference between what you'll imagine beforehand makes more sense vs. what you know will actually work afterwards. The key difference is that you know more than you did in the latter case, so your descisions later have more information to guide them and thus are more likely to be correct. To think you understood everything before you started and insist on sticking to that after you find it's not working out isn't rational, it's stubborn.