There are only a few respected conferences where you get to see new faces. The rest usually cycle through their top speakers.
The worst is when you have the same white 5 males talking about diversity.
Running a conference is a financial risk. You have to bring in enough attendees to ensure that you'll break even on costs. Because of that, organizers often bring in presenters with a known reputation for putting butts in seats.
To break into the circuit, find a conference with lower financial risks. For example, in the Microsoft database space, that's SQLSaturday, a free regional conference typically held at colleges. Those organizers don't have a lot of money on the line, so they can work on promoting their local speakers.
Even better, speak at local user groups and build up a reputation.
And, whether or not they're a direct draw, a reputation for giving good talks, not giving a sales pitch, not flaking out at the last minute, etc.
For better or worse, it's just a lot safer for conference organizers to accept talks from known quantities. Unfortunately, this makes it harder for unknown quantities to break in and (often) means that there is less variety of topics and perspectives than might otherwise be the case.
Building up a portfolio at user groups and other local events helps to some degree--especially if you've never spoken before. However, in my experience, just about every conference at its in crowd.
In my case, there are some conferences where I get accepted to speak regularly, some where I have a middle of the road batting average, and some where I mostly don't even bother to put in proposals any longer. And it's got very little to do with the topic area or the prestige/popularity of the event.
Personally if I'm going to a tech conference I want to hear about tech, not about HR. But if you want to have talks on diversity it makes sense the speakers on that topic would be largely representative of speakers generally, which is mostly white males.
