Honestly, there's still an argument to be made that compete.com is at least semi accurate. But Alexa is just a lost cause. It simply doesn't even resemble anything accurate anymore.

P.S. Happy Birthday HN

Actually, I'm surprised it's so high (150,637 as of today).

It means quite a lot of HN visitors (which are not necessarily just registered HN users) have installed Alexa toolbar.

Which is what ultimately Alexa rank mean. It is a huge source of bias - different types of sites have very different likelihood that their visitors would have installed Alexa toolbar.

Alexa shouldn't be compared to anything because their algorithm is heavily skewed. Use Compete, it's fairly accurate.

Probably because people that install spyware don't program or start their own companies, and hence don't read HN.