I think comparing going to a music festival for entertainment to using business resources (time and money) for a conference that presumably provides business value is a bit apples to oranges.

> that presumably provides business value

I have yet so see a conference that provided enough tangible "business value" to recoup its costs in any measurable sense. Let's be real: It is entertainment and stimulation for grownup nerds. Which is completely fine and has value for a business – but it is very much like a music festival.