Bitcoin was cheap and very easy to acquire in the first few years of its inception.
At the end of 2010, programmer Gavin Andresen bought 10,000 Bitcoins for $50 and created a website known as “Bitcoin Faucet” which gave out 5 Bitcoins to each user, worth only 5 cents back then.
That move was highly effective. Later on, someone imitated Gavin, building similar sites that gave small amount of Bitcoins to visitors. On the other hand, as these sites have large amount of traffic, they earned advertising fees by driving users to major Bitcoin sites. Around 50% of Bitcoin websites are dependent on them for traffic, making it a viable business model.