A few years ago, I became convinced that one feature would completely change my business. I didn't get customer feedback. I didn't validate demand. I didn't ask a single user if they actually wanted it. I just assumed they did. So I spent the next 4 months planning it, designing it, building it, fixing bugs, and polishing every little detail. I was genuinely excited because I thought this was going to be the thing that would make customers love the product. The day I launched it, I e...