Being seen as an "expert" in your field does positively affect your salary and giving talks is one way to help there. To what extent it helps I'm not sure. But that's not really the reason why I do it. I do it mostly because of ego. I see people tweeting about giving a talk at X convention and I feel like I should have that status.

As jrauser said, though, the more I do them the less inclination I have, as it really does negatively effect my ability to achieve other goals. And the older I get the other projects become more important to me.

As I wrote elsewhere in this thread, I write talks mainly because I want the finished talk to exist in the world. I think this is the same relationship an artist has with their art.

That said, having given some memorable talks[1] at high-profile conferences probably has helped my career more than a little bit.

[1] https://www.youtube.com/playlist?list=PLv3BG8BSXbeFNfR2Zk4n8...

Yes to both.

But that's not why I do it. It may sound trite, but I really do want to help others get better at stuff, and if I have something cool to share that I'm excited about, I'll go out there and share it.

If I help just one person in the room, that's a victory to me.

Speaking at a conference vastly increases its usefulness, especially if you get a slot on the first day, as people will then come to you for the rest of the conference to talk about stuff. It takes a bit of work up front (although - are there really people who rehearse for hours, apart from TED style performance-talks?) but it makes the conference itself easy cruising, and you get information and energy from it you never get when you're just listening to speakers and having to go 'hey, so who do you work for' a few dozen times over coffee breaks.