My first job coming out of university was organising conferences about the big business issues of the time, which was mainly the collapse of the Berlin Wall and the opening up of what was formerly communist Europe. 

Gradually the subject matter moved to the opportunities offered by new technologies, particularly the Internet. Back then, the key to a successful event was the subject matter that we could bring to knowledge-hungry delegates. We occasionally sold sponsorships or offered exhibition space to industry vendors but it was very peripheral to the main event which was the delegates' exclusive access to information. We made our money by charging attendees +/- $1,200 each.  

Over time, access to this type of information has become open to everyone, increasingly for free, which has reduced the importance of the presentations. In their place increasingly larger "ecosystem" trade shows have sprung up where attendees get to learn about the different vendors in a fast-moving space. As a result, delegates are not listening to the presentations and speakers are increasingly giving sales pitches. Organisers are now making more income from vendors whose sponsorship packages buy them access to delegates; while delegates frequently pay little or nothing to attend.

This shift has lead regular speakers like Anand Sanwal, CEO of CB Insights below, to conclude that his time is better spent writing than speaking since "content persists and reaches a bigger audience, so the ROI for us is demonstrably larger". 

The interesting point here is that the reason to attend an event remains the same - access to information that is for some reason unavailable without travelling at great time and financial expense. However, it is extraordinary that the difficult to reach information is now vendor guidance and advice on a particular topic. People want to engage with sales people without the commitment to buy. 

To me this suggests strongly that there is a failure of sales people (and marketing) to provide content that engages with the needs of their potential clients effectively on-line. And a big prize available to those that do.