Assuming there are HN/YC'ers with million+ users.
I haven't built anything solo with 1 million users, but I'm one of the 600,000+ people who helped build this:
http://drupal.org/home
...and it was done one user at a time, over a decade, nothing unethical, not much advertising beyond word of mouth. Lots of hacks, though!
I haven't built anything solo with 1 million users, but I'm one of the 600,000+ people who helped build this:
http://drupal.org/home
...and it was done one user at a time, over a decade, nothing unethical, not much advertising beyond word of mouth. Lots of hacks, though!