Plan the activity with a smaller group than you would want initially. Then invite others to an already organized event and rely on fomo to get people to go. Works great.

I have two small friend groups of four and in both is someone who often works weekend, so that's always fun trying to plan something, let alone if I want to have both groups somewhere. It was honestly a miracle I could get all 6 of them in one place at the same time somewhat close to my birthday.

Harsh but fair. It ensures that everyone can work their schedule out in advance, while also presenting clear expectations for participating in a voluntary hobby. Is there a consecutive number of missing sessions before being replaced? If not, how does the DM work it out in the campaign?

You have to be harsh, otherwise nobody gets to play. When we started our new group we made sure to inform everyone that playing DnD is not to be treated as a secondary hobby that can just be canceled for other stuff all the time. Make it your priority, plan other things around the sessions if you want to play with that group. Of course, any emergencies excluded but otherwise treat it as if it is your sport club training. If you miss too many sessions, you're out.

I know this sounds super arrogant and mean, but it's the only thing that works consistently. Also filters out friends who are not ready or able to commit that much time for playing.

I only run west marches style games now. The pcs need to be back in town by end of session or miss out on carousing or possibly worse depending on where they are. Each game is self contained so people can drop or join as they want.

What game?

Yeah this convo is either saying they're going to a bar which can be fun. Or they're 18-22 and drinking is as much about buying the alcohol as it is imbibing it.