Nobody warns you about any of this in the interview. You learn every one of them the expensive way. 26 harsh truths of product management: Everything is a P0. Yes, politics matter. Being glue can be a trap. Support knew before you did. Priorities change on a plane ride. Your guess became the deadline. Every reorg costs you a full quarter. Two engineers quietly decide what ships. The number of PM roles has stopped growing. Your roadmap has one item nobody believes in. Six people can block…