I failed so many times that I lost the count (over 200+ times) with my experiments. But i gained so much info from them and I even started a company. Nothing big but I felt joy of one success over the burden of failures.
What I learned is that I should create what I think it does amaze me and not really focus on the user side of things.
I sent you an email to your inbox mentioned in your user profile. Someone tried to sell me that website as well and I did some research about him (got his skype, his email, and even his address ).
I didn't know when it was going to happend but i knew it would. That 80m investment is nothing, imagine if they will use it to crack sha256 from bitcoins ? A 9-10 billion "business" opened for them.
Plus, privacy = lost
I've seen that implemented in the facebook graph, for example if you will look for "people who likes php" and start scrolling down, for each new "batch" of people a new request will be generated with those numbers.
That's why i assumed it was a formula/algorithm implemented, because it was generated at scrolldown.