Too Long; Didn't Read
Product Managers (PM) are responsible for the growth of the product from the very first day. If the product succeeds, the whole product team gets the credit but if it fails, the PM takes complete responsibility for its failure. PMs need to spend a lot of time with their product to make it simple and valuable for their users. With each passing day, you as a PM become so habitual of using your product that it restricts your ability to notice small flaws in the user experience and you start to overlook them.