What is the real ROI from conferences when the ticket prices are over $600 and sometimes even $1000? How many people pay this out of pocket rather than make their exmployer pay for it? I'm loooking at open source summit, kubecon etc.
At least in my place, there's a budget for such events, and employees are encouraged to attend. For an alternative model, look at the CCC congress. It is a community event, lots of people invest a lot of their spare time to make it happen.