> And it's not language- or topic-specific either: Java, JS, golang, cyber security, devops, all types of meetups really aren't what they used to be. You're lucky when you organize an event and more than 20% of registered people show up, even when you made them pay 10 bucks for it that they get back on arrival.

20% is pretty good. As long as you can find a free space, attendance shouldn't matter that much. It does vary by seasonality and weather though (very few people want to go to a tech meetup when it's great weather, or additionally if the weather is so bad they don't want to leave the house/office).