Although invention seems like a daunting task, we never really know what ideas we're going to have until we find ourselves in the right situation. It's for that reason that anybody I know who's invented something usually isn't doing too much bragging about it.
For instance, my grandfather apparently invented more than one piece of farm equipment and it took years before I ever found out about it. The way he saw it, he had a problem, he found a way to solve it, and that was it.
But in the moment, it's a lot easier to feel proud of what you've created and it's easier to share that pride with the world than ever. And I think it's fair to say that these people have a good reason to do that.