Almost every software engineer has a great talk idea in their heads. I know this because... engineers tell me about their ideas all the time.
Surprisingly, meetups and conferences struggle to attract enough speakers and proposals. There are so many interesting ideas that will never be shared, and I think that ought to change.
Whenever I meet someone who has a cool talk idea, I try to nudge them, "have you thought about speaking at a meetup?"
I almost always get the same response. I'm afraid. What if I look stupid? What if nobody is interested? What if someone heckles me?
By contrast, stand-up comedians actively look for smaller gigs to try out new material. Stand-ups know that only a few jokes will be good enough for the tour. The only way to unearth the good jokes is to test it on a real audience. Over time, jokes are polished and timing is tightened. By the time you watch the Netflix special, you're watching at least a year's worth of iterations.
Software engineers can benefit from a similar approach. If you want to prepare a great conference proposal, test out your material at meetups and pay attention to the response. When I have spoken at meetups, I listen carefully to see which points resonate with the audience. I write down the questions asked, and incorporate the answers into the next iteration.
Don't be afraid of the reaction, listen to it.