You let them get their way and watch them fall flat on their faces when they are clearly out of their depth and don't have the required experience to back up the grandiose claims. Or someone complains about it and they get called out by someone higher up (because said person didn't listen in the first place).
It's a huge waste of time and effort and really impedes productivity.
What you’ve said there is playing politics to an extent. I have a knack of pointing out projects that are going to fail and offering solutions, they often get ignored, they fail, and then I inherit the project. I’m lucky in that very few in my company are capable of doing my job and I’ve been promoted and had salary increases to keep me whenever I’ve handed my notice in.