Why do "well planned" projects still fall apart?

A few months ago, I sat in on a project retrospective. The plan was solid, the timeline was realistic, and the budget was approved. Still, the project finished six weeks late, and everyone was pointing fingers.

Turns out nothing broke technically. What actually happened: the sponsor stopped showing up after kickoff, two departments were optimizing for different KPIs, and by the time anyone noticed, decisions had already been made on outdated information.

I keep seeing this same pattern across construction, IT, and manufacturing projects. Technical skill gets a project started. Stakeholder management is what keeps it moving.

I work with PMA Indonesia, and this Saturday, August 22, we are running a free session on exactly this problem, called "Bridge the Gap: Stakeholder Management Secrets" with two speakers who have spent over 20 years dealing with this in real projects, not just in theory. If you want to sit in: https://www.pma-id.com/webinar-stakeholder-management?utm_source=chinh&utm_medium=whatsapp&utm_campaign=ssaallee

Genuinely curious though, for those of you managing projects right now: what is harder for you, getting stakeholders aligned early, or keeping them aligned once priorities start shifting?