If you’re always the one who plans, skip it once and see who steps up.

Organising becomes invisible work, and the group genuinely does not know you are doing it until it stops. That is not because they are ungrateful, it is because a plan that always arrives looks like weather. Skipping once is not a test designed to catch anyone out. It is the only way to find out whether the group plans or you do.

Let one week go by without sending the message. Do not hint, do not sulk, and answer honestly if someone asks. Either somebody steps up, which is good news, or nothing happens, which is worth knowing before you spend another year on it.