"According to publicly available data, there are now over 10 million bitcoin wallets. Perhaps the most informative statistic of all is the transaction volume: the number of transactions has also grown impressively, from roughly 80,000 a day to more than 200,000 without showing any signs of slowing."

I have several wallets. So wallets is not equal to users. If he can give every Skype user 0.001 bitcoin, he might make 100M users of  bitcoin.