Being a nimrod on Twitter aside...
He'll get more than that on the open market, but that doesn't mean he's worth it. It just means there are always teams out there that will pay whatever it takes to get someone. If the Rams have a valuation of $50m on him, and another team's desperation pushes that to 70, then that doesn't mean he's all of a sudden a top 5 CB. It just means that other team *thinks* he is.
It's not even my place to speculate about how much he's worth, because that's all relative to the eye of the beholder. He should try to get as much as he can. If he thinks he's the best corner in the league and wants his pay to be commensurate with that, then more power to him. Go get yours. But don't expect the Rams (or anyone else) to hold the same high opinion of your talent. That's not how negotiations work.