I believe virtual conferences are the wave of the future. I just returned from a 4-day genealogy conference in Salt Lake City. With the air travel, hotel expenses, restaurant meals, and conference admission, I spent more than $1,500 US. I also spent six days away from home: one day traveling to the event (in the cheapest airline coach seats I could find), four days at the conference, and one more day returning home. I am sure that attendees from overseas spent much more than I did.
Obviously, many people are not able to pay that much money or to take that many days out of their lives to attend such an event, regardless of their interest level. Luckily, technology can provide an alternative.