Earlier quoted context omitted.
Running servers costs money. And IIRC they were actually losing money even with the ads.
When did they stop hosting .torrent files? Hosting only magnet links means they have nearly nil bandwidth costs (just some sparse HTML pages, by far the biggest piece of content on a tpb results page are the ads) and require very little infrastructure. In contrast, they have banners on the results page, pop-ups when you interact on the results pages, and massive banners on the item pages. A good chunk of their client…
Even if 1/2 their traffic is using adblockers that still leaves billions of ad impressions a month. There is no reason to believe their lies about how much servers cost, especially on a site like HN where many people have first hand experience of more elaborate hosting costs and advertising.
2009 = 1b pageviews/month https://gigaom.com/2009/07/19/the-pirate-bay-distributing-th...
2014 = 90th most popular website on the entire internet, which itself grew massively in that 5 years