I added additional helpful information and photos to an article local to my area about a coal mine explosion that happened in the early 20th century. The original author came back and undid all of my changes because he was the "original author" which somehow gave him permission to do that. I had to appease his ego so that he would allow me to make the changes (that or I could have challenged him publicly, which I really didn't want to do.)
I can't speak for this author on Bitcoins... just my experience on Wikipedia.
Nothing, in theory. In practice, if you edit, they revert, you edit again, and they revert again, that is then an "edit war" and they can have the page locked for a while. It takes effort to make a change that even one person really doesn't want you to make - if they keep it up, you eventually have to go through the bureaucracy.