I've noticed in some niches, it's an opportunity for vendors to brainwash the attendees. Cybersecurity is one example. Vendors spend a lot of time pushing language around regulations, perceived risks, etc, that are "only solvable" with their expensive tools. And passing FUD about open source tools that solve the same problems as their paid tools.
Lots of little ways to push harder too, like giving out organizational or individual awards like "CISO of the year" to stroke egos. Or "free training" that's really pushing more sales.