Organizing a Meetup can be difficult, and sometimes the costs can add up too. Collecting payments can help in a number of ways.
First off, it can help to reduce no-shows since members are more likely to show up if they've paid ahead of time.
Charging also helps cover your costs. Need to reserve a venue, buy refreshments, or hire a speaker? Ask your members to help out!
Also, charging can help with regards to compensating some of your members. Does one of your assistant organizers spend hours every week organizing Meetup events? Go ahead and thank them for their hard work!
So, those are some things to keep in mind when deciding whether or not to charge your members.