but we usually end up in a couple of years great service, before they figure out that they could be earning money with serving ads or selling data.
The cycle is usually completed by another free service starting and being usable for the next few years, and in this case there's no pain in switching (no content you uploaded and spread URLs to), so I wouldn't worry.
On the other hand, in the age of HTML "hello world" including an Angular installation, downloading Bootstrap from external CDN, and at least three different kind of tracking scripts, I think sites like this one need to be praised loudly.
What Extratorrents and The Pirate Bay do tho seems to be something akin to clickjacking. I click on a link to a torrent search result (or a download link), a tab opens, and it immediately closes. Rest assured this generates them money.