You are wrong body they have 10000+ Sales daily buddy
i think they are earn by selling premium only...

Eg:
fileserve: $60/year, so $5/month, then $0.17/day

think they have 1 lakhs premium members - 1lakhs * 0.17 = $17k/day...

i read in fdc server once - 100gbit server cost 100k/month
(But sure fileserve will buy it in bulk for long contract, so it should be cheaper than 100k)
Fileserve must have 300-400 gbit(Rapidshare already have 600 Gbit)

so 400gbit = 100k * 4 = 400k/month, so $13.33K/day


So Net value = 17k - 13.3k = some amount(they will pay for uploaders + profit)

BUT SURE there will not be any change in $13.3K, but 17k(practically it possible for more than 25k)

Note:
filehosts without popup will increse their reputation, more reputation more sales(so they keep ads away...)


Exception:
Mediafire/duckload even have premium, they use popup ads
Sure each popup will gives atleast 5 mill($ 0.005) for US/UK - but you can expect atleast three popup

sure they may earn millions if adblock/popup addons are not present...lol

I am weak in mathematics..lol