Im not an expert obviously , but it was put to me that Bitcoins market cap is 195x moneros give or take , and therefore means that you have a bigger "anonymity set" , which I take to mean getting lost in a crowd. 
With all of Moneros privacy features, it doesn't account at all for its small anonymity set, which because of it's low market cap (2 billion or so) and its strong privacy features , actually prevent large players from investing, and so the market cap will remain small , and so too will the anonymity set.