But then one person in the audience likes what they hear or asks a really insightful question, and then next year they're giving their own talk about your work because they're using it and you realise it was worth it.
And I think a counterpoint to this, as a conference attendee, is that if you walk by a room and it's embarrassingly empty, then jump in, make eye contact with the speaker while they're talking, and ask a good question afterward, to help them out.
I'd much rather see a format where talks can be viewed or subscribed to individually, rated, and open to feedback/discussion.
One of those approaches is guaranteed to never get anything.
If you're just looking for presentations there are tons of webinars and virtual events.