theory: socialization is the main reason people go to bitcoin events.
I have never heard a person say “I came to hear ____ speak.”

They came to hang out. 

Brick and mortar bitcoin spaces and to a lesser extent meetups, have satisfied urban the need to socialize.  

Conferences have tragically failed at shifting with the market. 

No one cares about speakers. (unless they’re shitcoiners - then they care.)

If it’s not simple, fun in a special way and filled with great bitcoiners - less and less people will come.