I am still in confusion that how the browsers are doing there earning ????? Is there any perfect answers ????
I am not sure but may be they are earning from plugins providers. Browsers have a huge asset and that is popularity.
Mainly they get money from search engines. Search engines pay to have them used by default. Apple made about $1B from Google last year for example since Google is default in Safari. http://www.businessinsider.com/how-much-google-pays-apple-for-search-on-the-iphone-2012-3