There are two types of speakers that are important for a successful conference: Superstars and Superstories.
Superstars are big names. When potential attendees see that person's name, they think, "Wow. I want to go to the conference to hear her speak!"
Superstories are people with a powerful narrative to tell. This could be their own life story, a project they are working on, or research they have completed.
Some speakers are both, like Yeonmi Park. They are the ideal individuals to invite to a conference because they both bring people out and provide high quality content to the audience.
But some people are only one or the other. It's difficult to fill a conference solely with individuals who both are Superstars and have Superstories. In that case, it's okay to have some people who are just big names to draw out more attendees, as well as some people who have great stories that you want your audience to hear.
When thinking about the line-up for your conference, be sure you include both types of speakers: those who can bring people out, and those who can provide substantive information the audience will take home with them.