I think Ronda, and most other people are just oblivious to the fact that Captain Marvel is going to be cast next year so Marvel can have Carol Danvers in Infinity War. Marvel has plenty of time to make the movie, but casting is within a year:
http://screenrant.com/captain-marvel...eo-avengers/2/
Trust me, Marvel probably has their top picks, lined up, they just want to wait until they finished the script. Now, as bad as the majority of Marvel fans may think casting Ronda Rousey is, trust me, Marvel knows that Ronda as Captain Marvel would be far worse than we could ever imagine.
On a side note, I really hope someone kicks Ronda's ass in the octagon. Sure, it's not a very nice thing to say, but winning every single UFC match must do wonders to her self-esteem, like thinking that Marvel would ever consider her for the role. I'm thinking, she probably just needs to brought down a peg or two.